Every celebrity needs a marketable name. Which is why sometimes, their real names just don't make the cut. Here's a list of some 13 celebrities who decided to either cut short their name or used a different one altogether. And it works!

1. Tom Cruise

His real name is Thomas Cruise Mapother IV. Which makes it hard to remember, so he went along and shortened the whole thing to just Tom Cruise.

2. Katy Perry

Katy Perry wouldn't be as sexy and wouldn't be able to sell as many records as she does right now if she used her birth name: Kathryn Elizabeth Hudson.

3. Demi Moore

Demi was born Demetria Gene Guynes. And we're sure it would be incredibly hard to remember. She married Freddy Moore in her first marriage, and decided to shortened her name to Demi and hold on to her first husband's name.

4. Fergie

Fergie's real name is Stacy Ann Ferguson. Which sounds like a clerical worker somewhere in a post office. After marrying Josh Duhamel, she changed her name to Fergie Duhamel.

5. Dakota Fanning

Dakota became the youngest person ever to be nominated for a Screen Actors Guild Award. But would she have been able to do it if she used her real name: Hannah Dakota Fanning?

6. Lady Gaga

You'll never remember Lady Gaga's real name. Which is why she had to use a stage name that soon became a cultural icon. She was born Stefani Joanne Angelina Germanotta.

7. Nicki Minaj

Nicki was born Onika Tanya Maraj. Thank goodness for stage names.

8. Meg Ryan

Meg Ryan's real name is lengthy: Margaret Mary Emily Anne Hyra. That doesn't sound like a famous movie star, so she had to use a stage name.

9. Lana Del Rey

Lana del Rey was born as Elizabeth Grant, which actually isn't that bad. But that probably suited the career of an actress more than a singer.

10. Lorde

Like Gaga, you'll never remember her real name. She was born Ella Marija Lani Yelich-O'Connor.

11. Helen Mirren

Helen Mirren's name already sounds regal, but she was born with an equally regal one: Ilyena Lydia Vasilievna Mironoff. Sounds like some Russian Czar royalty doesn't it?

12. Tina Fey

Tina Fey wouldn't be half as funny if she used her real name: Elizabeth Stamatina Fey.

13. Miley Cyrus

Miley Cyrus has the worst real name on this list. She was born Destiny Hope Cyrus. Now, you wouldn't expect Destiny Hope to be doing all that twerking without associating that with porn now would you? So she used Billy Ray Cyrus's nick name as a small child - "Smiley", and cut out the S.

14. Olivia Wilde

Olivia Wilde has a pretty normal last name - Jane Cockburn. Okay, so that's not quite normal. Cockburn wins an Oscar. Doesn't sound right does it? She shed her family name after being inspired by her high school role of Gwendolen in Oscar Wilde's "The Importance of Being Earnest".

15. Iggy Izalea

We all know this can't possibly be someone's real name. But she couldn't possibly use her real one either: Amethyst Amelia Kelly. No star power.