Joanna Page will appear in the 'Doctor Who' anniversary episode.
The 'Gavin and Stacey' actress attended a read-through of the script on Monday for the long-awaited 50th anniversary special episode of the BBC One sci-fi show.
Joanna is the latest name to be announced in the all-star line-up which includes former Time Lord David Tennant and his beloved sidekick Billie Piper as well as 'Tinker Tailor Soldier Spy' actor John Hurt.
This marks the first time David will reprise his role since his last appearance as the time-traveller on January 1, 2010. Billie is set to return as companion Rose Tyler, who she played for two series following the show's reboot in 2005.
Current Time Lord Matt Smith and his brand new sidekick Jenna-Louise Coleman - who portrays Clara Oswald - will also star in the 3D episode.
Joanna expressed her desire to join the 'Doctor Who' cast back in 2010, saying she wished rumours of her joining the show were true.
She said: "A friend was telling me about that. I was like, 'I wish it was true'.
"I think I've got to be the only Welsh actress who has never been in 'Doctor Who' so if someone would like me to be in 'Doctor Who' I would love the part."
Filming for the 50th anniversary starts this week.