Bob (Houdini and The Space Cuckoos)

From Tardis Wiki, the free Doctor Who reference

Bob was a imaginary companion of the Eleventh Doctor. The Doctor chose the name to be a short for either "Robert" or "Roberta" so the companion could be of any gender. The Doctor spent time narrating the story to Bob and asking for help in making decisions, such as how to escape from a giant glass box filled with water. (PROSE: Houdini and The Space Cuckoos)