Deacon John Leavitt (1608–1691) was a tailor, public officeholder, and founding deacon of Old Ship Church in Hingham, Plymouth County, Massachusetts, the only remaining 17th-century Puritan meeting house in America and the oldest church in continuous ecclesiastical use in the United States. Hingham's Leavitt Street  is named for the early settler, whose descendants have lived in Hingham for centuries.
Leavitt was born in 1608 in England, but his exact birthplace is uncertain. Leavitt first appears in the annals of the Massachusetts Bay Colony in 1634, when he is shown in records of Dorchester, Massachusetts, as having been granted a house lot. Within two years, the early settler had moved to nearby Hingham, where he was granted land in 1636. In his early history of Hingham, attorney Solomon Lincoln recited the oft-told tale of Leavitt's supposed origins:
"The family tradition concerning John Leavitt is that he was an indented apprentice in England," wrote Lincoln in 1827, "and that he absconded from his master and came to this country when nineteen years of age.... He received a grant of land in this town in 1636. His homestead was in Leavitt-street, recently so named, on both sides of the river."
In the same year, Leavitt took the Freeman's Oath of the Massachusetts Bay Colony. In records on file at Boston Leavitt is shown on March 3, 1636, as pledging loyalty to the English Crown. In the early Massachusetts record the early English settler is listed as John Levett, as the tailor apparently spelled his own name for several decades, until it became corrupted later in life.
After moving to Hingham, Leavitt's first wife Mary died, and he subsequently remarried at Hingham on December 16, 1646, Sarah Gilman, daughter of Edward Gilman Sr., a fellow Hingham resident who later removed with his family to Ipswich, Massachusetts, and thence to Exeter, New Hampshire, where the Gilman family became well-known businessmen, statesmen and American patriots. Sarah Gilman's sister Lydia married Daniel Cushing, who became Hingham's town clerk  and John Leavitt's lifelong friend and, later, witness to his will.
Leavitt became active in Hingham town affairs, was named a Sergeant in the militia, as well as Deputy to the Massachusetts General Court from 1656–64, a Selectman  for the town in 1661 and many subsequent years, and then Deacon of the church, pastored by Rev. Peter Hobart, whose daughter Bathsheba married John Leavitt's son John Jr.
In between his public life and helping raise 13 children, Leavitt embarked on a lifelong pursuit of land, perhaps in recognition of its limited availability in his native England. By 1665, Leavitt and Lieut. John Smith, with whom he frequently collaborated in his real estate dealings, had secured 12 acres (49,000 m2) on the border of Hingham and what is today Cohasset. Living nearby Leavitt's house lot in today's Hingham Center, located at some distance from the main village, was his friend Nathaniel Baker, who also often purchased real estate with Leavitt. The two men apparently enjoyed particularly warm relations with the local Indians. Deacon John Leavitt assisted in the burial of a local Indian chief, and Baker was fined 20 shillings for "entertaining a Indian or Indians contrary to a Town order."
Nearby Leavitt's home described as 'over the Delaware' (River) was the so-called Great Rock, an enormous boulder subsequently blown up in the nineteenth century for building material. Onto its granite face was incised, by an early settler, a large inscription noting the accomplishments of Hingham's earliest settlers. The inscription read:
"When wild in wood the naked savage ran,
Lazell, Low, Loring, Lane, Lewis, Lincoln,
Hersey, Leavitt, Jacobs, King, Jones and Sprague,
Stemmed the wild torrent of a barbarous age,
And were the first invaders of this country,
From the Island of Great Britain, in 1635."
In keeping with the spirit of the inscription, and despite his own warm relations with the local Native American tribe, John Leavitt bought enormous tracts of land  from the local Indians, for a meager outlay of cash. Leavitt made several such purchases during his lifetime, most lying in the so-called 'Narragansett country,' in the region south of Hingham near the Massachusetts-Rhode Island border. One such tract, fifteen-miles (24 km)-square, was purchased by Leavitt and his friends Capt. Joshua Hobart  (twin brother of Rev. Peter) and Lieut. John Smith. In many such deeds, John Leavitt the settler is called 'John Levet' or sometimes 'John Levett' or even 'John Levit,' but rarely John Leavitt.
By May 3, 1680, when a town meeting was held to decide whether a new meeting house would be built upon the site of the old, John Leavitt was Deacon of the church, and one of the chief proponents for the new building. Leavitt's speeches on the need for a new sanctuary ultimately proved persuasive. The Old Ship Church, so-called because the hammerbeam roof construction recalled that of an upside-down ship's hull, was completed July 26, 1681, when the townspeople of Hingham gathered on the knoll bordering on Bachelor's Row (now Main Street) to watch the raising of the frame of the new building.
Observing the festivities was Deacon John Leavitt, aged seventy-three, who had argued the need for the new wooden edifice. The Deacon's pew remains set aside today in the building, over 300 years later. Tailor John Leavitt died at Hingham November 20, 1691, at age 83. His voluminous will records the disposition of the extensive lands accumulated during his lifetime, as well as documenting the family and social connections that sustained him in the New World. The executors of Leavitt's estate, named in his will, were his friend and brother-in-law Daniel Cushing Sr., Hingham's longtime town clerk, Capt. John Smith, Capt. John Jacob, Lieut. Matthew Cushing, and Daniel Cushing Jr.
Leavitt's widow, Sarah (Gilman) Leavitt, died in Hingham at the home of her brother-in-law Daniel Cushing on May 26, 1700. Two of John Leavitt's sons, Samuel  and Moses, later moved to Exeter, New Hampshire. John's son Israel, bearing another Old Testament name, married Lydia Jackson of the Plymouth Colony, where her grandfather Nathaniel Morton, the colony's Secretary and nephew of Governor William Bradford, was first to publish a list of signers of the Mayflower Compact, as well recording the celebration of the first Thanksgiving. Each year The Wall Street Journal carries an excerpt from Morton's New England's Memorial – printed at Cambridge in 1669, the first history book printed in America – limning the details of the first Thanksgiving.
The daughters of John Leavitt similarly left their mark. Hannah Leavitt married as her second husband Capt. Joseph Estabrook of Lexington, Massachusetts. John's daughter Sarah married as her second husband Samuel Howe—their descendants established the Wayside Inn in Sudbury, Massachusetts, celebrated in Henry Wadsworth Longfellow's Tales of a Wayside Inn.
Among the couple's other descendants on the continent they helped pioneer are Salem clipper ship owner, Massachusetts legislator and founder of the Peabody Essex Museum Dudley Leavitt Pickman; former Supreme Court Justice Sandra Day O'Connor; Philadelphia society portraitist Cecilia Beaux; architect Richard Morris Hunt, painter William Morris Hunt and brother Leavitt Hunt, attorney and photography pioneer; deaf Harvard astronomy wunderkind Henrietta Swan Leavitt; former Assistant Secretary of Defense during the Cuban Missile Crisis Roswell Leavitt Gilpatric; the abolitionist brothers Roger Hooker Leavitt, Joshua Leavitt and Hart Leavitt; New Hampshire native Dudley Leavitt, publisher of Leavitt's Farmers Almanack, the second oldest in the nation; and Hartford Mayor and father of the U. S. Dept. of Agriculture Henry Leavitt Ellsworth.
Deacon Leavitt's descendants also include writer Stephen King; former United States Secretary of Health and Human Services Mike Leavitt; New York City financier David Leavitt, namesake of Chicago's Leavitt Street for his role in rescuing nearly bankrupt Illinois and Michigan Canal; Hon. John Leavitt Stevens, U. S. State Dept. Minister to the Kingdom of Hawai'i, forced to resign in 1893 when accused of conspiring to overthrow Queen Lili'uokalani; Forest Ranger and later U.S. Congressman Scott Leavitt of Montana; and former Utah governor and U.S. Ambassador to China and Singapore Jon Huntsman, Jr. Among John Leavitt's English descendants was Admiral of the Fleet Sir Alfred Dudley Pickman Pound, a torpedo expert who masterminded Britain's victory in the Battle of the Atlantic (1939–1945).
Other descendants of the Deacon became German citizens. David Leavitt Jr., son of the New York banker, moved to Dresden, where daughter Louise Walcott Leavitt married Baron Franz Oswald Trützschler von Falkenstein. Her sister Helen Hudson Leavitt married Baron Adolf von Strahlenheim. Hugh Toler Leavitt, brother of the Baronesses, became a German Army officer.
- History of the Town of Hingham, Massachusetts, Vol. I, Part I, Historical, Published by the Town, 1893, Thomas Tracy Bouvé and others, University Press, Cambridge, Mass., 1893
- John Leavitt's Family Gathers in Hingham for his 400th Birthday, The Patriot-Ledger, June 30, 2008
- History of the Town of Hingham, Massachusetts, Vol. II, Thomas Tracy Bouvé and others, Published by the Town, University Press, Cambridge, Mass., 1893
- John Levett, Oath of Freeman, Boston, March 3, 1635-6, Records Relating to the Early History of Boston, Boston Registry Dept., Municipal Printing Office, Boston, 1900
- History of the Town of Hingham, Plymouth County, Massachusetts, Solomon Lincoln, Jr., Caleb Gill, Jr. and Farmer and Brown, Hingham, Mass., 1837
- Dictionary of American Family Names, Oxford University Press, ISBN 0-19-508137-4
- John Levett, whose English name became John Leavitt in America, and New Hampshire settler Thomas Levet, whose name became similarly corrupted to Thomas Leavitt, were the first to carry the name in America. The corruption in spelling, not unusual in an era of 'flexible phonetics,' distinguishes the American descendants from the original English family. Although the corruption into 'Leavett' was seen in England, the corruption into 'Leavitt' was not. The closest thing in English records was John Leavett, Gent., of Sussex, enrolled at Magdalen College, Oxford in 1590, who was alternately listed as 'John Levett.' 
- The surname of Leavitt's first wife Mary is unknown, but it may have been Lovett.
- Searches into the History of the Gillman or Gilman Family, Alexander William Gillman, Printed by Elliot Stock, London, 1895
- Two of John Leavitt's children later removed to Exeter: son Samuel by Leavitt's first wife; and son Moses, child of John Leavitt and Sarah Gilman, whose father lived by that time at Exeter.
- New England Family History, Vol. III, Henry Cole Quinby, Office of Publication, New York, 1910
- While serving as Hingham's third town clerk, Cushing kept a remarkable journal of goings-on in the town, which included notations on current gossip as well as the formal record of the town's events. Cushing's journal was later reprinted in a photographic format with reproductions of his pages in his striking penmanship.
- The Genealogy of the Sprague's in Hingham, Hosea Sprague, Published by Hosea Sprague, Hingham, 1828
- "Hubberd, Peter (HBRT621P)". A Cambridge Alumni Database. University of Cambridge.
- New England Families, Genealogical and Memorial, Vol. I, William Richard Cutter, Lewis Historical Publishing Co., New York, 1915
- Deacon John Leavitt's grandson Joseph Leavitt married Judith Hobart, daughter of Rev. Peter Hobart's son David and his wife Joanna Quincy, daughter of Edmund Quincy of Quincy, Massachusetts.
- History of Norfolk County, Massachusetts, 1622–1918, Vol. I, Louis A. Cook, The S. J. Clarke Publishing Co., New York, 1918
- A Narrative History of the Town of Cohasset, Massachusetts, Edwin Victor Bigelow, The Committee on Town History, Press of Samuel Usher, Boston, 1898
- In return for their land grant, the town required Smith and Leavitt to pay the local Wampanoag Chief Josiah. That payment for the 12-acre grant, made exactly 30 years after Englishmen had settled Hingham, was considered sufficient recompense to the Indians for the entire township, which the colonists had never purchased. With Smith and Leavitt's payment to the Indian Sachem Josiah, the town considered the matter settled.
- Historical Collections, Being a General Collection of Interesting Facts, Traditions, Biographical Sketches, Anecdotes, &c., Relating to the History and Antiquities of Every Town in Massachusetts, John Warner Barber, Published by Warren Lazell, Worcester, Mass., 1848
- The Clapp Memorial: Record of the Clapp Family in America, Ebenezer Clapp, Printed by David Clapp & Son, Publishers, Boston, 1876
- John Levet (eventually Leavitt), Hingham, MA, 1661 deed from Native Americans, Suffolk Deeds, Suffolk County, Mass., 1894
- The land on which Old Ship Church stands was purchased by the town from Capt. Joshua Hobart.
- A Discourse Delivered to the First Parish in Hingham, Sept. 8, 1869, Calvin Lincoln, Published by the Parish, James F. Cotter & Co., Boston, 1873
- John Leavitt's gravestone and remains are today in the graveyard at Hingham Center, not far from Old Ship Church. He was probably initially interred in front of the church, and was among the early settlers whose graves were moved when the road in front of the house of worship was widened, necessitating removal of the earliest graves, which were located in front of the church instead of behind it, where the church's current graveyard was later located. Leavitt's tombstone and remains were then likely moved to the Hingham Center cemetery, closer to the ancestral Leavitt home.
- Will (dated November 30, 1689) of John Leavitt, Deacon, at Rootsweb
- There was extensive intermarriage between the early Hingham families, and that was especially true of the Cushings and the Leavitts. There were Hingham residents named Cushing Leavitt -- and Leavitt Cushing.
- Samuel and Moses were half-brothers: Samuel descended from John and his first wife Mary; Moses from John and his second wife, Sarah Gilman.
- Ancient Landmarks of Plymouth: Part II, Genealogical Register of Plymouth Families, William T. Davis, A. Williams and Company, Boston, 1883
- The Writing of American History, Michael Kraus, Davis D. Joyce, University of Oklahoma Press, 1990 ISBN 978-0-8061-2234-2
- New England's Memorial, Sixth Edition, Nathaniel Morton, Congregational Board of Education, Boston, Mass., 1855
- Hannah Leavitt's first husband was Joseph Loring.
- History of the Town of Lexington, Middlesex County, Massachusetts, Vol. II, Charles Hudson, Lexington Historical Society, Houghton Mifflin Company, Boston, 1913
- Genealogy of the Estabrook Family, William Booth Estabrook, Andrus & Church, Ithaca, N.Y., 1891
- Her first husband was Nehemiah Clapp
- Admiral Sir Dudley Pound, Cover, TIME magazine, April 22, 1940
- British Admiral Dudley Pound, named for his Massachusetts Dudley ancestors, was a descendant of Salem East Indies merchant Dudley Leavitt Pickman, whose granddaughter married Richard Saltonstall Rogers.
- Obituary of David Leavitt, Jr., The New York Times, Sept. 17, 1897
- A third Leavitt daughter, Josephine, married Max Erwin von Arnim.  Christa von Arnim, granddaughter of Josephine and Max von Arnim, married Ernst August, Prince of Lippe and claimant to the family title of sovereign of the Principality of Lippe. A fourth Leavitt daughter, Emma Hall Leavitt, married architect and sportsman Christopher Wolfe of New York.  The father of the four Leavitt women, David Leavitt Jr. – son of banker David Leavitt and his wife Marie Emma (Hart) Leavitt – lived for many years at Dresden, while maintaining another residence at Great Barrington, Massachusetts. David Leavitt Jr. died at Dresden on September 16, 1897.
- Historical Commissions, Hingham Historical Asset Inventory, Town of Hingham, Massachusetts Archived 2008-07-23 at the Wayback Machine.
- Historical Highlights of Hingham, Massachusetts, hingham-ma.gov Archived 2010-07-17 at the Wayback Machine.
- John Leavitt's Family Gathers in Hingham for His 400th Birthday, The Patriot-Ledger, June 30, 2008
- Memorial to the children of John Leavitt and Sarah Gilman, Hingham Cemetery, Hingham, Massachusetts, flickr.com
- Gravestone of Israel Leavitt (died 1696), Hingham Center Cemetery, Hingham, Massachusetts, flickr.com
- Gravestone of Margrett (died 1739, wife of Josiah) Leavitt, Hingham Cemetery, Hingham, Massachusetts, flickr.com
- Gravestone of Josiah Leavitt (died 1708), Hingham Cemetery, Hingham, Massachusetts, flickr.com
- Leavitt Street sign, Hingham, Massachusetts, flickr.com
- Gravestone of Josiah Leavitt (died 1717), Hingham Center Cemetery, Hingham, Massachusetts, flickr.com
- Gravestone of Deborah Leavitt, wife of Joshua Leavitt, (died 1789), Hingham Center Cemetery, Hingham, Massachusetts, flickr.com