CBBC presenter Andrew Hayden-Smith is set to star in two episodes of the next series of sci-fi drama Doctor Who.
He'll appear as a good character called Jake Simmonds in episodes five and six, which will also see the return of the Doctor's old enemies, the Cybermen.
The episode will also star Roger Lloyd-Pack, who plays Trigger in Only Fools and Horses.
Andrew told CBBC Newsround: "I am so excited about joining one of the most famous programmes on TV."
"I am a real fan of David Tennant and can't quite believe I am going to be in the show. It's an absolute dream job for me. I can't wait to get started," he added.
Loads of guest stars
Earlier this week the BBC announced other top celebs will be joining the Doctor on his space travels in the new series.
Tracy-Ann Oberman from EastEnders and Anthony Head from Buffy will appear as villains.
Filming for Doctor Who starts next week, so Andrew won't be appearing on CBBC for a while, while he films the episodes.
The new series of Doctor Who begins in 2006.