Emilia Clarke Was Not the First Choice to Play Daenerys Targaryen on 'Game of Thrones'

Tamzin Merchant was set for the pivotal role that Clarke took over.

Emilia Clarke in "Game of Thrones" and Tamzin Merchant in "The Tudors"

It's hard to imagine anyone but Emilia Clarke playing the fiery Daenerys Targaryen on "Game of Thrones," but she almost didn't end up with the role.

When the HBO drama shot its pilot episode in late 2009, British actress Tamzin Merchant portrayed the then-naive, innocent Dany. But Merchant -- who starred in Showtime's "The Tudors" as Henry VIII's fifth wife, Catherine Howard -- had to leave the project for unknown reasons.

[Related: Jaime Lannister vs. Brienne of Tarth: Who's the Better 'Game of Thrones' Fighter?]

After the series was picked up in spring 2010, HBO announced that Clarke, a relative newcomer at the time, would take over. As Clarke recalled to HeyYouGuys.co.uk, "Tamzin had the role and they filmed the pilot internally so HBO were the only people that saw it. Once they decided to give the whole show the go-ahead, they decided to do a number of recasts."

At the time, Clarke had recently graduated from Drama Center London, but she was struggling to land roles when she got the call that would change her life. Before auditioning, though, she had a lot of research to do.

"I had never heard of the books" by George R. R. Martin, Clarke admitted to the New York Times, "and so I spent 48 frantic hours Wikipedia-ing."

[Related: How Kit Harington's Lost Keys Almost Derailed 'Game of Thrones' Season 3]

She, of course, won the role, which has turned her into a worldwide name. Merchant, meanwhile, went on to star in BBC's "The Mystery of Edwin Drood."

As Clarke noted, Daenerys wasn't the only part that was recast. Jennifer Ehle ("Zero Dark Thirty," "The King's Speech") played Catelyn Stark in the pilot and was later replaced by Michelle Fairley. Ser Gregor "The Mountain" Clegane was recast between Seasons 1 and 2, with Ian Whyte taking over for Conan Stevens. And Richard Dormer will play Beric Dondarrion, a recurring character in Season 1 who will have a larger role in Season 3.

"Game of Thrones" Season 3 premieres Sunday, 3/31 at 9 PM on HBO.