The M*A*S*H character written out in season 8 after Gary Burghoff left the series was Radar O’Reilly.
Radar, whose full name is Walter Eugene O’Reilly, served as the 4077th’s company clerk and was known for his uncanny ability to anticipate incoming helicopters and requests. Burghoff had played the character in both the 1970 film and the television series, making Radar one of the franchise’s most recognizable links between versions.
Although Burghoff completed his regular work after season 7, he returned for the season 8 two-part farewell “Good-Bye Radar.” In the story, Radar’s Uncle Ed dies, and Radar receives a hardship discharge so he can return to Iowa and help his family run the farm. Klinger gradually takes over his company-clerk duties.
This departure is sometimes confused with earlier exits: Henry Blake was written out at the end of season 3, Trapper John left after season 3, and Frank Burns departed during season 5. Radar’s exit was a season 8 storyline specifically built around Burghoff’s departure.