Pat Gelbart, an actress and singer who played Lt. Nelson in the Season 3 episode “Payday” using her professional name, Pat Marshall, passed away earlier this month (on December 11th) at the age of 94. She was married to Larry Gelbart, her second husband, from 1956 until his death in 2009.
Eagle-eyed M*A*S*H fans may have noticed “Pat & Larry Marshall” scrawled on the Red Cross sign in the Officers’ Club. In a November 1998 post to the alt.tv.mash newsgroup, Larry Gelbart revealed he wrote the names on the sign, presumably as a funny tribute to his marriage.
According to Internet Movie Database profile, she acted in the 1947 movie Good News and the 1975 movie The Prisoner of Second Avenue. An obituary in The Hollywood Reporter says she was also a house singer on the late night talk show Tonight Starring Steve Allen, which ran on NBC from 1954 to 1957.
(Thanks to Dan.)