Superheroes aren't the only ones with alter egos. Pop stars adopt them with increasing frequency so that the can satisfy a creative urge and to craft a character or a concept related to their music or the promotion of it. But they also are able to step outside of themselves and be someone or something else.

Simply adopting a nickname, changing a hairstyle (or color) or saying there is an alter ego at play is not enough. A true alter ego has a unique look, a style and a reason for existing outside of the artist's real self.

That's why we've selected these pop stars as having the best alter egos, since they are fleshed out and feel like real, existing people or pieces of the pop star's personality.

  • Jo Calderone

    Lady Gaga's alter ego Jo Calderone, a brooder with a black coif and an eerie similarity to 'Karate Kid' actor Ralph Macchio, turned up in Gaga's "You & I' video. He also took her place at the 2011 MTV VMAs, walking the red carpet, opening the show and presenting Britney Spears with her special VMA, but not before attempting to make out with her. As for why Gaga let Calderone take center stage at such a maj event, her former creative director Laurieann Gibson said, at the time, that it furthered the notion of Gaga as a performance artist. "The idea of her being a performance artist -- and it's starting the performance on the red carpet and the idea that the performance never ends for her -- is the first time I've experienced this with an artist," Gibson explained. "That's something that is specific to her, and the whole night was the performance, and it was important that Jo was a part of the whole night." We admit it -- we sorta harbored a secret crush on Jo. He was such a loner, a rebel.

  • Sasha Fierce

    While Beyonce told Allure that she killed off Sasha Fierce back in 2010 because she no longer needed her, there was a time when Sasha was necessary and we think she still exists, even if she is buried deep within the consciousness of her creator. Bey designed this sensual and aggressive alter ego strictly for her stage performances. Miss Fierce –- she can only be a princess because, well, Bey is the queen -- was born during the making of one of Bey's smash singles. The singer once revealed, "Sasha Fierce was born when I did 'Crazy in Love.' People, when they meet me, expect that all the time, but that person is strictly for the stage." So no, it's is not Sasha Fierce who does a little somethin' somethin' with Jay Z, aka the Hova. She exists/existed merely for her stage presence and that's that.

    Ezra Shaw, Getty Images
  • Roman Zolanski

    Roman Zolanski, clearly a play on 'Rosemary's Baby' director Roman Polanski, is one of the many alter egos of the Queen of the Barbz. Roman represents the antithesis of Nicki Minaj, who described him as "so flamboyant, so outspoken, so open, and, you know, creative." Roman allows the booty-shaking, baby-voiced and Queens-accented rapper to get atomic at times. As stated, Minaj has other alter egos, but Roman is perhaps the most fleshed out and best liked, besides that of her Minajesty. The rap vixen is said to have a whopping 15 alter egos, and some of them speak with British accents. Normally, we'd assume she'd need medication for that but all her alter egos are fun and unpredictable.

    Frederick M. Brown, Getty Images
  • Slim Shady

    Eminem's alter ego is such a part of the rapper and his overall presentation that we almost forget that he is indeed an alter ego that is indicative of the other side of Marshall Mathers and serves a very specific purpose. He is the evil side of Eminem, and the one that the rapper often blames in his lyrics when bad things happen. Em's most violent songs are often told from Shady's POV. Interestingly, Em did not employ the alter ego as much on 'Recovery,' his comeback smash, because he felt it didn't fit. But he can be revived at any time. Em's the boss. Or is Slim? Nevertheless, Em's alter ego is not frivolous. He has a defined role.

    Frederick M. Brown, Getty Images
  • Kathy Beth Terry

    In her 'Last Friday Night (T.G.I.F.)' video, Katy Perry created a now-iconic alter ego, if only for the space of a song and a video. Kathy was just 13, with her head gear, braces, nerdy glasses and overall not chic geekiness. More importantly, she was likeable and relatable. It allowed Perry to be the queen bee of geeks, and became as identifiable as her 'California Gurl' wigs, which she burned as she began promoting her third album 'Prism.' KBT is eventually made over to become the life of the party, but her geekiness still defines her. You can take the girl out of the geek clothes, but you can't take the geek out of the girl and that's why this playful alter ego is SO memorable in the pop universe.