The Daily Mirror said Piper, 23, is leaving her role of Rose Tyler because she does not want to be typecast, BBC News reported Saturday.
"We are not commenting on the third series, we are still working on the second series," a BBC spokesman said. "Rose has a whole new journey and a fantastic set of adventures to go on with the brand new Doctor, starting in the special on Christmas Day."
Piper has played the sidekick role since the BBC's revival of the popular sci-fi series earlier this year.
Obama 'selfie' photographer speaks out: 'Photos can lie'
Mena Suvari shares her delightfully awkward Christmas card photo