Pudsey
Pudsey Bear as the Doctor describes several different Pudseys in Looking for Pudsey.
Talk about it here.
Pudsey Bear was associated with Children in Need. Whilst he was in the Blue Peter studio, he was mistook for a minion by Greg James who then apologized. (NOTVALID: Mind My Minions)
He was a temporary companion to the Twelfth Doctor and Clara, he helped defeat Sontarans, Daleks, Colony Sarff and the Mire. (NOTVALID: Doctor Who Game Maker)
The Twelfth Doctor was later contacted, to help in search for former companion, by Eddie Redmayne. (NOTVALID: Looking for Pudsey)
Behind the scenes
He was added as a companion for one week during Children in Need.
More info at Children in Need.