Last Halloween, the American Ballet Theater principals James Whiteside and Daniil Simkin took a class dressed as stars from the troupe’s past, to the delight of observers. Mr. Simkin was Mikhail Baryshnikov. But Mr. Whiteside turned heads as the ballerina Gelsey Kirkland, with leotard and skirt, pointe shoes and fake hair in a bun. The choreographer Jessica Lang, scouting for dancers, was impressed: “He’s not afraid to push boundaries.”

Pushing boundaries is something of a habit for Mr. Whiteside, 32, who joined American Ballet as a soloist in 2012 and became a principal a year later. Yes, he professionally plays Prince Charmings, but he also leads alternative artistic lives: as a pop singer, JbDubs, and drag queen, Uhu Betch.

Ballet remains rather traditional when it comes to romantic pairings, gender roles and sexual expression. “I became very aware of the hetero-normative standard in ballet very early,” said Mr. Whiteside, who realized he would mainly play straight men onstage. “And that made me sad. I will never get to express myself as my true self.”

JbDubs and Uhu Betch help fill that gap.

Those characters have helped Mr. Whiteside attract an eclectic collection of fans on social media, including young, gay male ballet dancers who tell him his presence is reassuring. Some older ballet fans, however, are perplexed, and at times dismissive. “When I post a drag photo,” Mr. Whiteside said, “or if I post something off-color or nontraditional, I notice that I lose followers.”