Jerry/Daphne
In a manic portrayal by Jack Lemmon, bull fiddle player Jerry transforms into "Daphne" and genuinely creates what at times seems like a completely different—and quite female—character. Before donning drag, Jerry was a worrywart, a practical and put-upon sidekick to the more risk-taking and liberated Joe. He has fun, but he doesn't know how to loosen up; his idea of a good use of his meager musician's paycheck is going to the dentist and getting a filling. "Daphne" allows Jerry to loosen up and tap into his playful side. As "Daphne," Jerry is reactive, romantic, bold, and free. He delights in spending time with the girls in the band, seeking to forge a close connection with Sugar (to limited success). On his romantic date with Osgood, he basically falls in love with the millionaire, taking his role as eligible female very seriously and forgetting that he is a man altogether. He relishes the thought of a marriage to Osgood, and delights in the prospect of marrying a bachelor and finally becoming wealthy. It takes Joe's insistence to snap Jerry out of his fantasy and remind him that he is a man.
Joe/Josephine/Junior
Joe is Jerry’s best friend, a tenor saxophone player who uses his considerable charm to manipulate women (and Jerry) into doing whatever he wants. At the start, Jerry is staring at the women in the chorus line at the speakeasy, and in contrast to Jerry's dental concerns, wants to spend his paycheck gambling at the dog races. He is not always the most practical man, but he is proactive and crafty. "Josephine" is Joe’s alter ego when they join the all-girl band. "Josephine" is quite a lady, somewhat stand-off-ish and not as playful as Jerry's "Daphne." As "Josephine," Joe becomes one of Sugar's main confidant, a kind of wiser older sister to Sugar's naive romantic. Yet another character that Joe puts on is that of oil tycoon and millionaire "Junior," a cold man, who prefers classical music to jazz and has never been able to feel anything sexual towards women since a terrible event in his romantic past left him traumatized. As "Junior," Joe struggles to affect the air of a blue-blooded heir, but his failings go largely unnoticed by the wide-eyed and equally naive Sugar, who falls for him without questioning the authenticity of his character.
Sugar Kane
The sexy lead singer and part-time ukulele player of the all-girl band that Jerry and Joe join undercover, Sugar is a naive, earnest, and as she says herself, "not very bright." At the beginning, she is portrayed as a lush, always looking for a drink to drown her sorrows and her loneliness. She is also, however, exceedingly charming, exhibiting a lovable innocence at every turn, which endears other people to her, especially Joe and Jerry. Sugar describes herself as always getting "the fuzzy end of the lollipop" because she constantly falls for saxophone players who leave her high and dry. Now she’s on the lookout for a brainy millionaire type with glasses. Tenor sax player Joe uses this inside information that he gets as "Josephine" to set himself up as precisely that, and the two fall in love.
Osgood Fielding III
The all-girl band has been booked to play a hotel in Florida which is mainly populated by wealthy older men who have migrated south for the winter. One of the many older millionaires looking to find younger women is Osgood Fielding III, an eccentric millionaire who says he has been married seven or eight times and who sets his leering eye upon "Daphne." He is lascivious and will not take "No" for an answer, eventually wooing "Daphne" with a night of dancing at the hotel.
Spats Colombo
Named for his natty footwear, Spats is a stone-faced and unflappable mob boss. He runs the speakeasy at which Joe and Jerry work in the beginning, which gets raided by the police early on. To get revenge on another mobster, Toothpick Charlie, for telling the police about the speakeasy, Spats kills Charlie and his friends in the garage where Joe and Jerry just happen to be picking up a car for a gig. After they flee certain death, Joe and Jerry encounter Spats yet again when he comes to a mobster convention at the very same hotel where they are hiding out. Spats is killed by Little Bonaparte.
Detective Mulligan
Detective Mulligan is hot on the trail of Spats immediately after the massacre and follows him down to the Florida hotel where Spats, Jerry and Joe are all staying. Mulligan is probing and tough-as-nails, perfectly suited for his tasks of bringing violent, corrupt mobsters to justice.
Sweet Sue
The bandleader of the all-girl band that Joe and Jerry join. She is the only one associated with the band who senses that there is something "off" about "Daphne" and "Josephine." She is very protective of the girls in her band, not wanting them to drink on the job.
Bienstock
The traveling manager of Sweet Sue and Her Society Syncopators. Sweet Sue has a domineering habit of yelling “BEINSTOCK” whenever one of the girls in the band causes trouble.
Little Bonaparte
Bearing more than a little physical resemblance to former Italian dictator Mussolini and with a name that recalls the iconic movie gangster played by Edward G. Robinson in Little Caesar, Little Bonaparte is the mob boss of mob bosses, who has determined that Spats Colombo has got a little too big for his spats. Little Bonaparte is himself the mastermind behind the mobster convention at the Florida hotel, the setting for his murder of Spats.
