Jenna-Louise Coleman has joined the BBC One sci-fi series as The Doctor's (Matt Smith) new companion, but her character name has yet to be confirmed.
Coleman will first appear in the upcoming seventh series of the show at Christmas, replacing current companions Amy Pond (Karen Gillan) and Rory Williams (Arthur Darvill).
Fans attending the filming of Coleman's first episode have claimed that they overheard producers and cast members calling her Clara.
"Jenna Louise is CLARA," one fan tweeted.
The actress revealed back in March that she knew little about the character, including her name.
Doctor Who will return to BBC One in the autumn, with the series seven premiere debuting at this year's Edinburgh International Television Festival.
Watch a trailer for the upcoming series of Doctor Who below: