Virginia O’Brien, the singer-comedienne who garnered the nickname “Miss Frozen Face” for her signature deadpan delivery in MGM’s musicals of the 1940s, died Thursday at the Motion Picture & Television Hospital in Woodland Hills. She was 81.The daughter of the captain of detectives for the L.A. Police Dept. and niece of popular film director Lloyd Bacon, she was discovered by Louis B. Mayer while making her stage debut in a Los Angeles production of “Meet the People.” She appeared in “Keep off the Grass” on Broadway in 1940 with Jimmy Durante, Ray Bolger and Jackie Gleason among several starts, and as a result was signed by Columbia Records to sing four songs from the score of that show. O’Brien crooned “Rockabye Baby” to the Marx Brothers in “The Big Store” (1941) and “Bring on the Beautiful Men” to Fred Astaire and Lucille Ball in “Ziegfeld Follies” in 1946. She also made memories with her rendition of “The Wild, Wild West” while playng Judy Garland’s singing sidekick in “The Harvey Girls” and her parody of “In a Little Spanish Town” in “Thousands Cheer” was a standout amid performances by an all-star cast. O’Brien married actor Kirk Alyn in 1942 and co-starred opposite her husband’s friend, comedian Red Skelton, in six films, then joined Donald O’Connor for one of his comedy films about the talking mule Francis in “Francis in the Navy” in 1955. She divorced Alyn that year and retired from films, although she continued to work in theaters and nightclubs during the 1970s and ’80s, and made numerous guest appearances on variety shows. In 1976, O’Brien returned to the screen in the Disney picture “Gus,” starring Ed Asner and Dick Van Patten. She is survived by three daughters, a son, seven grandchildren and two great-grandchildren.