Could I be sued for using the name of a celebrity for a fictional character?

No. Names can't be copyrighted which means you can use the name Idris Elba for your book. But why would you want to? It's a pretty distinctive name so it's likely that anyone who reads your novel will either connect your character with the actor, or they'll think you copied the name because you couldn't think up your own.

Absolutely you can be sued if you do not get Mr. Elba's permission. No matter how much you think your character is not similar to the man, you are not writing about Joe Smith. If the book does see print (any editor worth his salt will tell you to change the name) you - and the company - can be sued for everything you were paid plus the value of future sales plus damages. The Editor will also risk termination. You are buying trouble just to have a good time.

If you really get published, your publisher will take care of that for you, but I imagine you'll self-publish, so mostly no one will ever see it. Why not just change the name? If the character has nothing to do with Idris Elba, then why use that name? Is the rest of your novel also as unimaginative?

I'd say Ms. Elba's legal team could sue you. Arabella's right that names can't be copyrighted, but they can be trademarked. Ms Elba's name has recognition value and can be used as her brand name. Cary Grant was the professional name of Archie Leach, and though I did see a character named "Archie Leach" in a book, I doubt I'll see a "Cary Grant" that did not refer to him as the actor Cary Grant. "Elvis Presley" can mean only Elvis Presley, not just because Lisa Marie Presley and her mother own the rights to the name via "Elvis Presley Enterprises" but because anyone who reads "Elvis Presley" in a book will associate the name only with the King of Pop. It has "recognition value" because of his fame.

You'll also get a few responses - some nasty - from readers who recognize the name of the actress. "How dare you use her name?" and "She's not like that!"

Yes you can. Look it up.

What they said ^