William Hallett (1616 – 1706), an early English colonizer in America, was born in 1616 in Dorsetshire, England.

Hallett's arrival in America is not definitively documented, but by 1647 in Connecticut, he married his second wife, Elizabeth Fones Winthrop Feake Hallett. Elizabeth was the niece of John Winthrop, the first governor of the Massachusetts Bay Colony. Her first husband died by drowning, and she divorced her second husband due to mental illness. When Elizabeth married William while pregnant with their first child, it caused a scandal in the Puritan colony. The Puritan church didn't recognize mental illness as grounds for divorce, and the townspeople of Connecticut, upon learning they were considered "living in sin," demanded Elizabeth be hanged.

John Winthrop Jr., Elizabeth's uncle and the governor of Connecticut, intervened. He struck a deal with Peter Stuyvesant, allowing the Halletts to flee to New Amsterdam. Under the cover of darkness, Elizabeth left behind all her property, and they sailed to Hell Gate in Newtown, present-day Hallets Cove. Stuyvesant appointed Hallett Sheriff of Flushing around 1650. However, he later imprisoned Hallett for hosting an Episcopalian minister. Hallett was eventually forgiven.

In 1652, William Hallett purchased 160 acres of land, which became known as Hallett's Cove. Twelve years later, his holdings expanded to include all of present-day Astoria, encompassing roughly 2,200 acres. The area remained largely rural and used as a ship landing until 1839 when fur merchant Stephen A. Halsey officially founded Hallets Cove. A steamboat and ferry line were then established, connecting the area to 86th Street in Manhattan.

The original farmhouse at Hallett's Cove was burned down by indigenous people, forcing the Hallett family to flee to Flushing. Despite this setback, they persevered and built a life in the new world, becoming part of early American history. Elizabeth's actions in Connecticut helped establish women's property rights, while William's banishment and reinstatement played a role in setting the stage for future protests like the Flushing Remonstrance. The couple eventually left the Anglican church and converted to Quakerism.

William Hallett died in April 1706 in the area now known as Hallets Cove in Newtown, Queens, New York Colony, British Colonial America.

A fictionalized account of their marriage appears in the book The Winthrop Woman by Anya Seton.