Rose-the-cat

Rose-the-Cat was a cat the Tenth Doctor adopted after Rose Tyler was trapped in Pete's World. He decided that Rose was the perfect name for the cat. Rose, K9, and the Doctor lived together without any other long term companions.

Rose would often try to help the Doctor cope with the loss of his former love, through various means. Most to all of these failed.

Rose eventually left the TARDIS team, searching the cosmos for a new person to comfort as the Doctor decided it was time to find a new companion. After an immesurable amount of time in stasis, Rose emerged to find the real Rose Tyler standing in front of her pod in a state of confusion. (COMIC: A Rose by Any Other Name)