Leonard's birth name was Leonard Lebitsky and he was sometimes called Fat Jack. As was the case with many rising comics in the 1950s, his exposure on The Tonight Show hosted by Jack Paar put Leonard over the top. He became a busy performer on television and in nightclubs. He worked steadily in the big rooms of Las Vegas, insulting the high-rollers and losers who needed a laugh.
Leonard's comedic method was sarcastic and aggressive, creating an "insult humor" genre which anticipated Don Rickles. (Appropriately, a Friars' Club roast in honor of Rickles was emceed by Jack E. Leonard, who introduced Rickles as "a man who's been doing my act for about 12 years now!") Jack E. Leonard's strong and unapologetic on-stage personality ("Good evening, opponents!") belied a gentle and giving spirit that all of his friends knew well, and which would occasionally be revealed in his act when he would perform against type and sing a sentimental song. A trademark joke, always getting a big laugh, was when he would take off his hat revealing his bald head and then would ask, "What did you expect, feathers?" He also referenced his weight problem in his act.
He wore a distinctive outfit: a dark suit which was purposely two sizes too small, a white narrow-brimmed hat, and horn-rimmed glasses. On one variety show, Leonard's contemporaneous popularity was demonstrated when a lookalike came onstage and did a Leonard-like schtick. Then Leonard himself walked onstage and addressed his doppelgänger: "You've got a great future, son... but not in this business!"
Leonard made occasional recordings and motion pictures in addition to his many television appearances.
He collapsed onstage at a New York venue at age 63 and subsequently died from complications soon after undergoing heart surgery.
1957 "Rock and Roll For Kids Over Sixteen", Vik LX-1080 mono.
1964 "How To Lose Weight With Fat Jack"
1967 "Scream On Someone You Love Today"
Leonard narrated the theatrical release The World of Abbott and Costello: not a documentary, but a compilation film consisting entirely of clips from Abbott and Costello movies. Leonard's narration consisted entirely of wisecracks and bad jokes, offering no real information about Bud Abbott or Lou Costello or their films.
