Lucy Jefferson (October 10, 1752–1811), also known as Lucy Jefferson Lewis, was a younger sister of United States President Thomas Jefferson and the wife of Charles Lilburn Lewis.
Born in Albemarle County, Virginia, she was the eighth of Peter Jefferson and Jane Randolph Jefferson's 10 children. She was nine years younger than her brother Thomas Jefferson. She was born into an elite planter family and would have been educated at home by her mother, together with her sisters. Their father died when they were young.
At age 17, Jefferson married her first cousin, Charles Lilburne Lewis, on September 12, 1769. He was related to Meriwether Lewis, who had helped lead the Lewis and Clark Expedition. The couple eventually had eight children: Randolph, Isham, Jane Jefferson, Lilburne, Mary Randolph, Lucy B., Martha, and Ann (Nancy).c/e
Jane and Mary had married before 1806 and established their own households. The remainder of the Lewis family moved to Livingston County, Kentucky in 1806 or 1808, following their grown sons Randolph and Lilburne and their families. Charles and Lucy Lewis built a plantation called "Rocky Hill" near the present-day town of Smithland.