Although frequently mentioned and referred to by Margaret Houlihan, the character of LTC Donald Penobscott only appears in person in the series twice, and was portrayed by two different actors: Beeson Carroll in "Margaret's Marriage," and Mike Henry in "The M*A*S*H Olympics."
Reported to have been intended as the swan song for the character of Margaret, as she finally got married to the career military man of her dreams, flying off with him to Tokyo, leaving the dead-end affair with Frank Burns behind. However, actress Loretta Swit came back for Season 6 and Larry Linville did not, so Margaret's character continued to be fleshed out and Burns was replaced by Maj. Charles Emerson Winchester III.
After Hot Lips drives everyone crazy by gushing over him and describing him ad nauseam throughout the entire fifth season, her fiancé, Lt. Col. Donald Penobscott (played by Beeson Carroll) makes his first appearance.
During the 'smoker' Col. Potter tells Lt. Col. Penobscott that Klinger was a gypsy, that's why he was wearing earrings. Klinger posed as the gypsy king Zoltan during the episode "Hawkeye Get Your Gun" earlier in the season.