Alienist is an archaic term for a psychiatrist or psychologist. Despite falling out of favor by the middle of the twentieth century, it received renewed attention when used in the title of Caleb Carr's novel The Alienist (1994). Although currently not often used in common parlance, the term "alienist" is still employed in psychiatric hospitals to describe those mental health professionals who evaluate defendants to determine their competency to stand trial.
The term also appears in Harry Houdini's first feature silent film "The Grim Game", written by Arthur B. Reeve and John W. Grey, and adapted for the screen by Walters Woods. A Parmount-Artcraft Picture from 1919 with Houdini as as "Harvey Hanford, star reporter for The Daily Call newspaper. Alienist was used to describe the doctor "Dr.Tyson, a famous alienist and Cameron's physician." played by Arthur Hoyt. Harry Houdini plays "Harvey Hanford" a young man who is wrongfully jailed for murder and must escape to save his fiancé "Mary Wentworth".
Director: Irvin V Willat; Photographed by: J.O. Taylor; Art Director: Wilfred Buckland; Starring: Harry Houdini as "Harvey Hanford, D. Cameron's estranged nephew", Thomas Jefferson as "Dudley Cameron, childless eccentric millionaire miser", Ann Forrest as "Mary Wentworth, D. Cameron's ward and heiress"
When Kris Kringle is put “on trial” in the film Miracle on 34th Street (1947), several newspaper articles call the psychiatrists who examined him "alienists".
The film Stonehearst Asylum (2014), set in 1899, uses the term "alienist" to refer to doctors who treat asylum patients.
The film, "His Girl Friday," (1940),  uses the term to describe the doctors who interview a convicted cop killer to determine his sanity.
"Two Alienists Report Alleged Budd Slayer Has Some Abnormalities. Two alienists reported today to Walter A. Ferris, District Attorney elect of Westchester County, that Albert Fish, 64 years old, held in the county jail for the murder of Grace Budd, is legally sane.". The New York Times (White Plains, New York). December 27, 1934..
In Agatha Christie's novel The A.B.C. Murders (1936), Dr. Thompson, "the famous alienist", is called to Scotland Yard to help Poirot and Inspector Japp find a murderer who mails cryptic letters to Poirot before each murder.
It was used in the The Originals season episode "Red Door", where Mikaelson family patriarch Mikael calls Cami, a therapist, an alienist.
It was used in the Penny Dreadful episode "Possession", where Vanessa asks Dr. Frankenstein during an examination, "meaning you will soon bring in an alienist?", and in the episode "The Night Tennyson Died", Vanessa begins seeing Dr. Seward, played by Patti LuPone, who refers to her branch of science as "alienism".