The character played by Gary Burghoff in M*A*S*H was nicknamed Radar. His full name was Walter “Radar” O’Reilly, a young company clerk and later sergeant assigned to the 4077th Mobile Army Surgical Hospital.
Radar’s nickname came from his uncanny ability to sense incoming helicopters, wounded soldiers, and trouble before anyone else noticed. The series presented him as gentle, shy, and inexperienced, but also highly observant and deeply loyal to the unit. His glasses and youthful appearance reinforced his role as the camp’s innocent early-career soldier.
Burghoff first played Radar in the 1970 film M*A*S*H and continued the role in the television series, making him the only major performer to appear in both versions. Radar eventually left the 4077th after learning that his uncle had died and his mother needed him at home. The character is sometimes confused with Klinger, another enlisted soldier, but Klinger served mainly as an orderly and company clerk while Radar was the unit’s famously perceptive clerk.