Plenty of Hollywood's biggest names don't go by their birth names–Demi Moore, Tina Fey, Mila Kunis, and Dakota Fanning.
However, you probably don't know how the celebrities ended up with their current monikers.
Some are simple–Nicolas Cage, nephew of Francis Ford Coppola, changed his last name to make a name for himself without the worries of Hollywood nepotism.
Others, like Michael Caine and Martin Sheen are more inspired. And then there's Whoopi Goldberg, whose name was Caryn Johnson until friends noticed her flatulence problem.
Demi Moore — Demetria Gene Guynes
Moore kept the last name of her first husband Freddy Moore after they divorced in 1984.
Daughter Tallulah also legally changed her name to Lula. Father Bruce Willis first broke the news in 2007 on "The Late Show with David Letterman."
"She wanted me to mention here on the big show that she's legally changing her name from Talullah to Lula, just Lula," said Willis. "She doesn't like her name."
Reese Witherspoon — Laura Jeanne
The "Sweet Home Alabama" actress traded her first and middle name in for her mother's maiden name, "Reese."
Katy Perry — Kathryn (Katy) Hudson
Before she was a chart-topping singer, Perry was producing Christian music, under her birth name, Kathryn Hudson. She released gospel record Katy Hudson under the former label Red Hill Records before adopting her mother's maiden name to avoid confusion with this actress Kate Hudson.
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