The BBC One sci-fi drama's official Twitter feed stated that an "iconic" star will be confirmed at midnight.
The announcement read: "Casting news! An iconic star will be appearing in #DoctorWho and we've been granted permission to reveal who at midnight… See you at 00:00!"
With Doctor Who celebrating its 50th anniversary in 2013, several past stars of the show have been tipped to make a return in some form.
Tom Baker recently said that he would be interested in making an appearance next year.
Doctor Who will return with its seventh season premiere 'Asylum of the Daleks' in August.
The episode will debut at BFI Southbank in London on August 14 ahead of its assumed premiere date at the Edinburgh International Television Festival later that month.
Watch the trailer for the seventh season below: