Whovians have less than 20 days until the "Doctor Who" Christmas special, and this episode will reveal if Clara Oswald, played by Jenna Coleman, will stick around. If the character does stay, she could become the Doctor's longest companion.

Coleman's Clara, called the "Impossible Girl" by the Doctor, could break a record if she stays on for the ninth season. Her 30th episode will place her third, behind companions Amy Pond and Rose Tyler, as the longest standing companion, according to the Radio Times

Clara joined the Doctor in the second half of the Season 7. Peter Capaldi came in as the newest Doctor in Season 8. 

Karen Gillan will continue to be one of the most memorable. 

She starred as Amy Pond, and she was the companion to Matt Smith's Eleventh Doctor for 33 episodes, between April 2010 and Sept. 2012.

In second place is Billie Piper as the Rose Tyler for 27 episodes, alongside Tennant's Tenth Doctor, between March 2005 and July 2006. The Rose character returned several times to the series.

If Clara leaves, maybe fans will see the return of an old companion, though it won't be Donna Noble, a former Time Lord companion. Catherine Tate, who portrayed the unsinkable Donna, doubts that the character will make a comeback.

"Unfortunately I think Donna's storyline would prevent her from coming back, because any memory of the Doctor, of her time traveling with him and the adventures she embarked on would kill her," Tate said, Doctor Who TV reported. "So I can't see a storyline being able to bring her back."

Tate is enjoying Capaldi as the current Doctor.  

"I think Peter is wonderful in the role, and I'm really enjoying the eighth season. He's a fantastic actor, and his wit and intelligence shines," Tate said.

While the only time Tate has worked with Capaldi was on "Doctor Who" in an episode titled "The Fires of Pompeii," she has continued working with tenth Doctor David Tennant in British theater and on her TV show. Tate and Tennant have enjoyed working with each other so well that they would like to continue collaborating on future projects.

"Working with David is the best," Tate said. "We get on so well, and it's just always so much fun,"Zap2It.com reported.

Tennant has made several appearances on Tate's show "The Catherine Tate Show." The pair starred together in the 2011 stage production of "Much Ado About Nothing."

Whether Coleman decides to stay on, "Doctor Who" has already broken records.

The 50th anniversary TV movie special, "The Day of the Doctor," broke the Guinness Book of World Records for the most-watched simultaneously broadcast show. It was seen all over the world.

And, the role of the Doctor has had its fair share of breaking records, too. Tom Baker played the Fourth Doctor for seven years, from 1974-1981. Tennant was in the role for five years, 2005-2010.