William Bradford (1590 – May 9, 1657) was a leader of the Pilgrim settlers of the Plymouth Colony in Massachusetts, and became Governor of the Plymouth Colony. He was the second signer and primary architect of the Mayflower Compact. As Governor of Plymouth, Bradford is also credited as being the first to proclaim what popular American culture viewed as the first Thanksgiving.

He was the son of William Bradford and his wife Alice Hanson, and was baptised on March 19, 1590 in Austerfield, Yorkshire. At an early age, he was attracted to the "primitive" congregational church in nearby Scrooby. By 1607, he was a committed member of what was termed a "separatist" church, since the church-members had wanted to separate from the Church of England. When James I began to persecute separatists in 1608, Bradford fled to the Netherlands, along with many members of the congregation. These "separatist" Puritans went first to Amsterdam before settling at Leiden. Bradford married his first wife, Dorothy May (1597 – December 7, 1620), on December 10, 1613 in Amsterdam. While at Leiden, he supported himself as a fustian weaver.

Shifting alignments of the European powers (due to religious differences, struggles over the monarchies and intrigues within the ruling Habsburg clan) caused the Dutch government to fear war with Catholic Spain, and to become allied with James I of England. Social pressure (and even attacks) on the separatists increased in the Netherlands. Their congregation's leader, John Robinson, supported the emerging idea of starting a colony. Bradford was in the midst of this venture from the beginning. The separatists wanted to remain Englishmen (although living in the Netherlands), yet wanted to get far enough away from the Church of England and the government to have some chance of living in peace. Arrangements were made, and William with his wife sailed for America in 1620 from Leiden aboard the Mayflower.

Before the colony was established, Bradford's wife died. On December 7, 1620,
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Dorothy Bradford died while the Mayflower was at anchor in Provincetown Harbor. However, there are no contemporary accounts of the circumstances of her death, only a later mention of drowning by Cotton Mather in Magnalia Christi Americana.
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Bradford included only brief mention of her passing in his own writing. There is a widely circulated story that she committed suicide, but that is derived from a work of historical fiction published in the June, 1869 issue of Harper's New Monthly Magazine.
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The first winter in the new colony was a terrible experience. Half the colonists perished, including the colony's leader, John Carver. Bradford was selected as his replacement, in the spring of 1621. From this point, his story is inextricably linked with the history of the Plymouth Colony.

William Bradford's second wife, the also widowed Alice Carpenter Southworth, came to Plymouth aboard the Anne in July 1623, her two sons following after 1627 Stratton, Plymouth Colony - Its History & Peoples 1620-1691,p. 355-6 and married Governor Bradford on August 14, 1623 at Plymouth. They had three children, William, Mercy, and Joseph. Alice also helped to raise John, the son of his first marriage. William Bradford died at Plymouth, and was interred at Plymouth Burial Hill.

Some historians feel that Bradford's greatest achievement was introducing a system of privatized production. These historians contend that the colonists produced more farming for themselves, rather than for the community.