Allyn Joslyn was the son of a Pennsylvania mining engineer. On stage from age 17, Joslyn scored as a leading man in such Broadway productions as {~Boy Meets Girl} (1936) and {~Arsenic and Old Lace} (1941), appearing in the latter as beleaguered theatrical critic Mortimer Brewster. Joslyn's leading-man qualities surprisingly evaporated on camera, thus he spent most of his movie career playing obnoxious reporters, weaklings, and gormless other men who never got the girl.
Among his more notable film appearances were as Don Ameche's snobbish rival for the attentions of Gene Tierney in Lubitsch's Heaven Can Wait (1943), and as the jellyfish cardsharp who sneaks onto a lifeboat disguised as a woman in Titanic (1953). In the sprightly B picture It Shouldn't Happen to a Dog (1946), Joslyn was for once cast in the lead, even winning heroine Carole Landis at fade-out time. A prolific radio and TV performer, Allyn Joslyn played one-half of the title role on the 1962 TV-sitcom McKeever and the Colonel. ~ Hal Erickson, All Movie Guide. 