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An impostor (also spelled imposter) is a person who pretends to be somebody else, often to try to gain financial or social advantages through social engineering, but just as often for purposes of espionage or law enforcement.
Exposing impostors 
Notable impostors 
- Frank Abagnale, who passed bad cheques as a fake pilot, doctor and lawyer.
- Gerald Barnbaum, a former pharmacist who posed as a doctor for over twenty years after stealing the identity of a licensed medical professional.
- Joseph D. Bonnanno, who stole the identity of a dead infant and worked for eight years as a stockbroker and financial adviser after having fled prosecution in Massachusetts for stealing money from a furniture store. 
- Cassie Chadwick, who pretended to be Andrew Carnegie's daughter.
- Ravi Desai, a journalist who passed himself off as Robert Klinger, a fictional CEO of BMW's North American division, in a series of diary entries for Slate magazine.
- Arthur Orton, also known as the Tichborne Claimant, who claimed to be the missing heir Sir Roger Tichborne.
- David Hampton, who pretended to be the son of Sidney Poitier.
- Richard Allen Minsky, who scammed female victims for sex by pretending to be jailed family members over the phone.
- Frederick Emerson Peters, U.S. celebrity impersonator and writer of bad checks.
- Lobsang Rampa, who claimed to be a deceased Tibetan Lama possessing the body of Cyril Hoskins and wrote a number of books based on that premise.
- James Reavis, who claimed he owned Arizona.
- Christopher Rocancourt, who pretended to be a member of the Rockefeller family.
- Michael Sabo, who was known as a "Great Impostor" with over 100 professional aliases listed with the FBI.
- Wilhelm Voigt, who masqueraded as the "Captain of Köpenick".
- Victor Lustig, who sold the Eiffel Tower.
False nationality claims 
- Mary Baker, who pretended to be Princess Caraboo of Javasu.
- Youree Dell Harris, better known as Miss Cleo, claimed to be from Jamaica.
- Joseph Howard Lee, who claimed to be the African native Bata LoBagola.
- Korla Pandit, an African-American pianist/organist who pretended to be from India.
- George Psalmanazar, who claimed to be from Formosa.
False Royal Heritage Claims 
- Anna Anderson, who may have really believed she was the Grand Duchess Anastasia of Russia, daughter of Tsar Nicholas II of Russia.
- Bardiya, ancient ruler of Persia, widely regarded as an impostor but may have been genuine.
- Alexis Brimeyer, a Belgian who claimed connection to various European royal houses.
- Bhawal case, concerning a "resurrected" Indian prince who may have been genuinely who he was claimed to be.
- Mary Carleton who was, amongst other things, a false princess and bigamist.
- Count Dante is the real name of John Keehan. In his campaign to promote his system of martial arts, he also claimed victories in various secret deathmatches in Asia, and mercenary activity in Cuba, none of which carried documented proof.
- False Dmitriy I, False Dmitriy II and False Dmitriy III, who all impersonated the son of Ivan the Terrible.
- Harry Domela, who pretended to be an heir to the German throne.
- Tile Kolup, also known as Dietrich Holzschuh, was an impostor who in 1284 began to pretend to be the Emperor Frederick II.
- Eugenio Lascorz who claimed connection to the royal house of the Byzantine Empire.
- Terence Francis MacCarthy, styled himself MacCarthy Mór and "Prince of Desmond"
- False Margaret, who impersonated the Maid of Norway.
- Pierre Plantard, the mastermind behind the Priory of Sion hoax who claimed to be Merovingian, a pretender to the throne of France.
- Frederick Rolfe, who is better known as Baron Corvo.
- Lambert Simnel, a pretender to the throne of England.
- Eugenia Smith, another woman who claimed to be the Grand Duchess Anastasia of Russia.
- Charles Stopford, an American man who has claimed to be an English nobleman since 1983 using the name of a dead infant.
- Perkin Warbeck, a pretender to the throne of England.
- Yemelyan Pugachev, who claimed to be Peter III of Russia.
Academic impostors 
- Dr Charlotte Bach, a fringe evolutionary theorist who was not a doctor.
- Marvin Hewitt, who became a university professor without any credentials.
- James Hogue, who most famously entered Princeton University by posing as a self-taught orphan.
- Marilee Jones, Dean of Admissions at MIT and best-selling author who claimed advanced degrees in science fields. After ten years in the post, she was revealed to have only a high school diploma.
- Timothy Leslie McCormack, bogus aircraft engineer who personally conducted or signed off on dozens of maintenance checks on Qantas planes before being discovered. He had only passed one basic exam, and later was found to have forged character references in order to receive a lesser sentence.
- Lana Nguyen, who became a university professor with the credentials of her husband. She resigned when students complained of her lack of knowledge on the subject she taught.
- Adam Wheeler, who transferred to Harvard University by pretending to attend M.I.T. and to have graduated from Phillips Academy, and submitted false SAT scores.
False minority national identity claims 
- Forrest Carter, author of The Education of Little Tree.
- Carlos Castaneda, writer and self-styled anthropologist.
- Iron Eyes Cody, Italian American actor (the "crying Indian" in anti-litter commercials) who claimed to be a Native American.
- Jamake Highwater (aka Gregory Markopoulos, Jay Marks), author.
- Chief Buffalo Child Long Lance, an African American who claimed to be a Native American.
- Two Moon Meridas, herbalist and faux Amerindian.
- Grey Owl, an Englishman who wanted to be Ojibwa.
- Ward Churchill, a former professor of Ethnic Studies at the University of Colorado who claimed to be Cherokee, although his genealogy shows no non-white ancestry.
Multiple impostors 
- Frederic Bourdin, "the French Chameleon".
- Barry Bremen has entered multiple sporting events pretending to be an MLB umpire, an NBA All-Star, and Dallas Cowboys Cheerleader among other things.
- Ferdinand Waldo Demara, "The Great Impostor".
- Christian Karl Gerhartsreiter, German who claimed to be a member of the Rockefeller family among other things.
- Stanley Clifford Weyman
- Jerry Alan Whittredge, dubbed the "Great Astronaut Impersonator", arrested in 1998 after talking his way into NASA's Mission Control during a Space Mission, being given VIP tours of two Navy bases and receiving information about the space shuttle. He claimed to be an Astronaut, CIA Regent for Life, Medal of Honor winner and Top Gun Trophy winner, according to the affidavit of the arresting agent Joseph Gutheinz; he also claimed his attorney was President Bill Clinton.
- Laurel Rose Willson, who claimed to be victim of satanic ritual abuse "Lauren Stratford" and Holocaust survivor "Laura Grabowski" (see also Binjamin Wilkomirski).
Women who lived as men 
Many women in history have presented themselves as men in order to advance in typically male-dominated fields. It is unknown whether they identified as transgender in the current sense. See also: List of wartime cross-dressers.
- Joan of Arc, famous French heroine who disguised herself as a man to fight the English
- James Barry, who successfully lived as a male British military surgeon.
- Frances Clalin, who served in Missouri artillery during the United States Civil War.
- Nadezhda Durova, a woman who became a decorated soldier in the Russian cavalry during the Napoleonic wars.
- Catalina de Erauso, Basque nun-soldier under Spanish colonial army.
- Dorothy Lawrence, an English journalist who wore uniform during World War I.
- Hua Mulan, who disguised herself as a man to join the Chinese army, when her father was too old for it.
- Deborah Sampson, a female soldier during the American War of Independence.
- Mary Anne Talbot, an Englishwoman who became a sailor during the Napoleonic wars.
- Billy Tipton, jazz musician.
- Loreta Janeta Velazquez, who supposedly was a Confederate soldier under the name Harry T. Buford.
- Pope Joan, a woman who allegedly ruled as pope. Many doubt the historicity of this account.
Military impostors 
- Joseph A. Cafasso, former Fox News military analyst who claimed to have been a highly-decorated Special Forces soldier and Vietnam War veteran. He actually served in the U.S. Army for only 44 days.
- Alan Clayton, a self-employed pub chef who claimed to be an SAS veteran who received the Victoria Cross in a top-secret mission in the Middle East, had been wounded in combat, suffered from post-traumatic stress disorder, and claimed to have beaten lung cancer in order to meet Scottish First Minister Alex Salmond. Clayton never served in the military. 
- Wes Cooley, a former US Congressman who claimed to have fought in the Korean War. He served in the U.S. Army for two years, but was never in Korea.
- Arthur Rex Crane, former President of the Ex POW Association of Australia who claimed to have been captured by the Japanese and sent to work on the Burma Railway during WWII in order to claim service and disability pension payments. He was at school in Adelaide during the war and never served in the military.
- Brian Dennehy, a famous American actor who claimed to have fought in the Vietnam War. He served in the United States Marine Corps for four years, but was never in Vietnam.
- George Dupre, who claimed that he worked for the SOE and the French Resistance during World War II. Dupre served in World War II, but he was never in France or with the SOE.
- Joseph Ellis, American professor and historian who claimed a tour of duty in the Vietnam War. He served in the military during the war, but never left the United States.
- Jeff "Rock" Harris, personal trainer and body building judge who claimed to have been a highly decorated Army Ranger who earned numerous commendations during Operation Restore Hope. These claims have been refuted by Raleigh Cash and Matt Eversmann, two soldiers who served during the Battle of Mogadishu.
- Jesse Macbeth, anti-war activist who claimed to be an Army Ranger ordered to execute innocent civilians in Iraq. He was discharged from the Army as unfit for duty before completing basic training.
- Alan Mcilwraith, a call centre worker from Glasgow who, among other things, claimed that he was a decorated captain in the British Army. Mcilwraith had never served in the military.
- James Shortt, Director-General of the International Bodyguard Association, who at various times made false claims to have served in the British Special Air Service, Parachute Regiment and military and law enforcement units around the world. Shortt also made false claims to a number of knighthoods and titles of nobility as well academic, medical and martial arts qualifications and also styled himself as the "Colonel-Commandant" of a fictitious ancient order of bodyguards pledging their loyalty to the bogus Irish chieftain Terence Francis MacCarthy. before being exposed in the media after being dismissed as a consultant by Eye Spy Magazine in 2009. Shortt's actual military experience only amounted to a few months' part-time service in the British Territorial Army, during which time he did not complete basic training.
- Robert Stanley, who has stolen the identities of actual Navy SEALs and others, and along with his wife, Jennifer L. Stanley, frequently claims that they were or are Navy SEALs. There is no record of anyone by the name of Robert Stanley listed in the SEAL Database, and there never have been any female Navy SEALs as of January 2013.
- Friedrich Wilhelm Voigt was a German impostor who masqueraded as a Prussian military officer in 1906 and became famous as The Captain of Köpenick.
- Micah Wright, an anti-war activist who claimed to be an Army Ranger involved in the United States invasion of Panama and several other covert operations. He was an ROTC student in college, but never took a commission and never served in the military.
- Bampfylde Moore Carew, a Devonshire man whose popular Life and Adventures included picaresque episodes of vagabond life, including his claim to have been elected King of the Beggars.
- Alan Conway, who impersonated Stanley Kubrick during the early 1990s.
- Chevalier d'Eon, who lived the second half of his life as a woman.
- Anoushirvan D. Fahkran, a 27-year-old Iranian porn actor who legally changed his name to Jonathan Taylor Spielberg and posed as the 14-year-old nephew of legendary Hollywood director Steven Spielberg to enroll in high school.
- Lewis Peter "Buddy" Morgan, who started impersonating Randy Meisner, the former bass player of the Eagles in 1988. His identity was not conclusively revealed until 1997, after which he was arrested and spent 16 months in jail, but upon his release continued his charade and was still doing so as of 2006.
- Robert Hendy-Freegard, who posed as an MI5 officer.
- John Howard Griffin, who darkened his skin and travelled in the American South as a black man in 1959 to write Black Like Me.
- Alicia Esteve Head, known as Tania Head, who claimed to be a survivor of the 9/11 terror attacks.
- Pavel Jerdanowitch, the father of the Disumbrationist movement.
- Ashida Kim, believed by many to be Caucasian author and self-proclaimed ninja Radford Davis (alternate pen name Christopher Hunter), who wrote numerous books on ninjutsu during the '70s and '80s, noted for refusing to provide details about his teachers, or the lineage of the martial art in which he claims expertise.
- Enric Marco, who presided over an association of Spanish survivors of the Nazi camps when he went to Germany to work in the Nazi war industry.
- Guerdwich Montimere, a 22-year-old man who posed as homeless 16-year-old orphan Jerry Joseph and became the star of the Permian Panthers high school basketball team.
- Louis de Rougemont, who claimed to be an explorer.
- Steven Jay Russell, who has impersonated judges and a doctor among others.
- Treva Throneberry, a 31-year-old woman who became 16-year-old Brianna Stewart and impersonated other teenage girls.
- Arnaud du Tilh, who took the place of Martin Guerre in the 16th century and lived with Guerre's wife and son for three years before being discovered when Guerre returned.
- Graham Tumber, who despite looking nothing at all like him and despite using his own name, impersonated Status Quo frontman Francis Rossi for a year, duping Dover district council into providing free hospitality and transport services after promising to appear at a charity concert in the town.
- Binjamin Wilkomirski, a fake Holocaust survivor.
In fiction 
- The Count of Monte Cristo
- The Man in the Iron Mask
- Impostors are a common theme in the Blandings Castle series of novels and short stories.
- A Knight's Tale - A peasant poses as nobility to compete in a jousting tournament
- Big Momma's House - Martin Lawrence disguises himself as a rotund grandmother
- Catch Me If You Can - True story of Frank Abagnale Jr. who successfully conned millions of dollars worth of checks as a Pan Am pilot, doctor, and legal prosecutor
- Changeling - Based on true events, a Los Angeles woman is reunited with her missing son only to realize the boy is an impostor, while the police try to cover up the whole ordeal
- Coming to America - A rich African prince pretends to be poor
- Connie and Carla - Two women pose as drag queens
- Dave - A look-alike fills in for the President
- Face/Off - John Travolta and Nicolas Cage pose as each other
- House Guest - Sinbad pretends to be a rich dentist
- I Now Pronounce You Chuck and Larry - Two straight firefighters pose as homosexual lovers
- Impostor - 2001 Gary Sinise film based on a Philip K. Dick short story of the same name.
- The Imposter - A documentary about the 1997 case of the French confidence man Frédéric Bourdin, who impersonated Nicholas Barclay, a Texas boy who had disappeared at the age of 13 in 1994.
- Just One of the Guys - A female high school reporter poses as a teen-aged boy.
- Juwanna Mann - A male basketball player dresses as a woman to play in the WNBA
- Little Man - A diminutive, but adult, criminal pretends to be an infant
- Mrs. Doubtfire - Robin Williams disguises himself as an old British nanny
- The New Guy - A high school geek poses as a dangerous criminal to be more popular
- Overboard - A poor carpenter tricks a rich heiress into believing that he is her husband
- The Ringer - Johnny Knoxville pretends to be mentally challenged to enter the Special Olympics
- She's the Man - A female soccer star pretends to be a boy to play on their team
- Sister Act - A Reno lounge singer pretends to be a nun
- Some Like It Hot - Two men pretend to be women
- Soul Man - A white man undergoes treatment to appear black
- The Associate - A black woman disguises herself as a white man to get a job on Wall Street
- The Secret of My Success - A kid from the mail room pretends to be an executive
- Tootsie - A struggling actor pretends to be a woman
- Tropic Thunder - Robert Downey, Jr. plays an Australian actor who undergoes a "racial transplant" to play an African American role
- True Identity - A black man who disguises himself as a white man to escape the mob.
- Two Much - A man wants to date two different women, so he pretends to have a twin brother
- Victor Victoria - A woman poses as a drag queen
- Wedding Crashers - Two party crashers trick a wedding party into believing they were invited
- While You Were Sleeping - A subway fare collector fools a family into believing she was engaged to their comatose son
- White Chicks - Two black men disguise themselves as young white women
- Working Girl - A secretary takes the role of her boss, a player on Wall Street
- Zelig - A man yearning for social acceptance develops the ability to imitate features and habits of the persons around him.
See also 
- Capgras syndrome
- Miriam Coles Harris, author who was the victim of an impostor.
- Confidence trick
- Identity deception
- Identity theft
- Impostor syndrome
- List of Messiah claimants
- Political decoys
- Anzmi.net, more on cases.
- Heroes or Villains?, list of military impostors
- Revelations of imposture and substitution in field of history and culture
- "Famous Impostors". London: Sidgwick and Jackson. 1910. Retrieved 5 December 2010.
- Man jailed for stealing dead baby's identity 20 years ago and working as stockbroker
- Byron, By (2008-12-04). "Qantas phony uses MP as referee". Dailytelegraph.com.au. Retrieved 2012-06-26.
- "Fake Qantas engineer jailed". Heraldsun.com.au. Retrieved 2012-06-26.
- "Fake character references earn Walter Mitty real jail time". Smh.com.au. 2009-08-28. Retrieved 2012-06-26.
- "The E-Carillon". Carillon.uregina.ca. Retrieved 2010-09-12.
- Jacques Steinberg and Katie Zezima (May 18, 2010). "Campuses Ensnared by Life of Deception". New York Times. Retrieved 5 December 2010.
- Bogus Astronaut. ABC News, June 8, 2008.
- A High-flying phony pulls 1 over on NASA. New York Daily News, June 4, 1998.
- Man poses as astronaut steals NASA secrets. Reuters, June 4, 1998.
- Lies of a Walter Mitty who fooled Alex Salmond and impressed women
- November 26, 2010 3:08PM (2010-11-26). "Fake POW pleads gulity to 21 year pension fraud". Couriermail.com.au. Retrieved 2012-06-26.
- Mark, By (2010-12-21). "Fake POW gets real jail time for $460,000 welfare fraud". News.com.au. Retrieved 2012-06-26.
- "Kinston resident recalls extraordinary experiences in Army". Webcache.googleusercontent.com. 2012-06-13. Retrieved 2012-06-26.
- "Veterans contest 'Black Hawk' story". Kinston.com. 2011-07-07. Retrieved 2012-06-26.
- Posted: 7:02 AM, May 12, 2010 (2010-05-12). "Teen high school basketball star is 22-year-old impostor". Nypost.com. Retrieved 2012-06-26.
- Rebecca Camber (2008-11-14). "Conman posing as Status Quo star enjoys free meals and trips in mayor's limousine after tricking entire town for a whole year | Mail Online". Dailymail.co.uk. Retrieved 2010-09-12.