A boy seaman is a boy who serves as seaman or is trained for such service.

John Travers Cornwell VC, commonly known as Jack Cornwell or as Boy Cornwell, is remembered for his gallantry at the Battle of Jutland during World War I. Having died at the age of only 16, he was posthumously awarded the Victoria Cross, the highest award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces. Cornwell is the third-youngest recipient of the VC after Andrew Fitzgibbon and Thomas Flinn.