Shannon Wells Lucid (born January 14, 1943) is an American astronaut who holds records for the longest duration stay in space by a woman and the longest stay in space by an American. She has flown in space five times.

Lucid was born in Shanghai, China, to missionary parents, but grew up in Oklahoma. She attended the University of Oklahoma and obtained a Ph.D. in biochemistry from that school in 1973. She was selected to the NASA astronaut corps in 1978.

Lucid's first space flight was in June 1985 on Space Shuttle Discovery's mission STS-51-G. She flew on additional shuttle missions in 1989, 1991, and 1993.

Lucid is best known for her fifth spaceflight, when she spent 188 days in space, from March 22 to September 26, 1996, including 179 days aboard the Russian space station Mir. Both to and from Mir, she travelled on Space Shuttle Atlantis. Her stay on Mir was not expected to last so long but her return was delayed twice, extending her stay by about six weeks. During the mission she performed numerous life science and physical science experiments.

From 2002-2003, Lucid served as the Chief Scientist of NASA.

Lucid was awarded the Congressional Space Medal of Honor in December 1996, the 10th astronaut to be given that honor.