Cecil Lewis "Young Jack" Thompson (August 17, 1904 – April 11, 1946) was an American boxer who twice held the World Welterweight Championship.
Born Cecil Lewis Thompson, his name was changed when he decided to become a professional fighter.
He reeled off a series of wins, but also had a draw and a loss to future welterweight champion Young Corbett III.
In 1930 Thompson lost to Jimmy McLarnin but, in his next fight, won the welterweight title by beating his old rival Jackie Fields.
After four non-title bouts (including a loss to Young Corbett III), Thompson put his title on the line against Tommy Freeman in September 1930 and lost it by a fifteen-round decision.