Hugh Bainbridge

Hugh Bainbridge was a vampire who auditioned for the role of the Eighth Doctor's companion while posing as a human (BFA: Situation Vacant)

Hugh Bainbridge was the pseudonym a genetically engineered vampire named Drusis used, who put on a bumbling, amiable public school boy personality so that the Doctor's expectations of them would be low and he would be more impressed with him later when he did something heroic. Given that he is a vampire, he could not enter the TARDIS without being invited. He planned to drink the Doctor's blood so as to obtain his genetic material, allowing him to operate the TARDIS.