Jenna Louise Coleman

Doctor Who has a new companion — and her name is Jenna-Louise Coleman. The British actress has been cast to star alongside Matt Smith in the British sci-fi drama, BBC America announced Wednesday.

Coleman will replace Karen Gillan, who, in addition to Arthur Darvill, will make a "heartbreaking departure after one final series of roller-coaster voyages" later this year.

The 25-year-old actress joins the cast as the drama nears its 50th anniversary in 2013. "I'm beyond excited, I can't wait to get cracking; working alongside Matt I know is going to be enormous fun and a huge adventure," she said in a statement.

Doctor Who's Karen Gillan and Arthur Darvill to exit series next season

"It always seems impossible when you start casting these parts, but when we saw Matt and Jenna together we knew we had our girl," executive producer Steven Moffat said in a statement. "She's funny and clever and exactly mad enough to step on board the TARDIS."

Moffat, however, is mum about the details surrounding Coleman's character. "It's not often the Doctor meets someone who can talk even faster than he does, but it's about to happen. Jenna is going to lead him his merriest dance yet," Moffat said. "Who she's playing, how the Doctor meets her, and even where he finds her, are all part of one of the biggest mysteries the Time Lord ever encounters. Even by the Doctor's standards, this isn't your usual boy meets girl.

Doctor Who's seventh season is currently in production. It is slated to have 14 episodes.

Coleman is best known for her roles on the British soap Emmerdale and British drama series Waterloo Road. She made her big-screen debut in 2011 as Connie in Captain America: The First Avenger.