McLean Stevenson ( November 14 , 1929 -- February 15 , 1996 ) was an American actor . He is best known for his role as Henry Blake on the TV show , M \* A \* S \* H. He left the show in 1975 and his character was killed off . Edgar McLean Stevenson , Jr. ( November 14 , 1927 â `` February 15 , 1996 ) , better known as McLean Stevenson , was an American actor most recognized for his role as Lt. Colonel Henry Blake on the TV series M \* A \* S \* H. He was also recognized for his role as Michael Nicholson on The Doris Day Show .