Filming has begun on the fourth series of Doctor Who, with loads of new faces joining the Time Lord on his travels.
David Tennant is back as the Doctor, comedian Catherine Tate will play his newest assistant, while Freema Agyeman returns as his old one, Martha.
During this series, the Doctor will take on loads of new monsters, as well as his old enemy The Ood, which is a race of squid-like humans.
And the he'll also pay a visit to the famous crime writer Agatha Christie.
Other stars to sign up to the series include Felicity Kendal, a TV star from when your parents were little, and actor Tim McInnerny.
But before the new series begins in 2008, fans can look forward to a Christmas special set on the famous ship the Titanic, starring pop princess Kylie Minogue.