Jodie Whittaker has been seen filming the upcoming 13th series in Liverpool alongside newcomer John Bishop and some fans of the sci-fi show also believed they'd seen Tate around the site as will, according to the Daily Mail.
However, a representative for the comedian has said she is not on set.
“I can confirm Catherine is very much not in Liverpool and is not on [the] DR WHO set,” they told Radio Times.
Yahoo News UK has contacted a representative of Tate's for comment.
The 51-year-old made her first appearance on Doctor Who in the closing moments of 2006 series finale Doomsday with her story being picked up in the 2006 Christmas special The Runaway Bride.
Tate returned to the role in a full-time capacity for the fourth series as she became a regular companion alongside David Tennant's Doctor.
She also appeared as Donna in the 2009-2010 Christmas and New Year's specials.
Tate and Tennant were reunited for a skit last year as the comedian reprised her Lauren the Schoolgirl character.
Tennant played a teacher trying to handle the disobedient character in the sketch for BBC’s Big Night In, a fundraiser for Comic Relief and Children in Need.
Bishop joins Doctor Who as new character Dan, filling the gap left by Bradley Walsh and Tosin Cole.
Rumours have also circulated that Whittaker will step down from playing the Time Lord following the 13th series, however, the BBC have not commented on the claims.
Watch: Jodie Whittaker hasn't considered other roles since joining Doctor Who