This is a list of fictional creatures and aliens from the universe of the long-running BBC science fiction television series Doctor Who. The series first aired in 1963 before being cancelled in 1989, with a brief attempt to revive the show in 1996 being unsuccessful. The show was successfully revived in 2005, and continues to air episodes. The series stars an extraterrestrial known as The Doctor who is capable of changing their appearance when they die in a process known as regeneration. They travel through time and space in a machine known as the TARDIS. In the process, the Doctor often comes into contact with various alien species. This list only covers alien races and other fictional creatures and not specific characters. Additionally, several alien races re-appear in Doctor Who's spin-off series The Sarah Jane Adventures, Torchwood, and Class, though antagonists original to those series do not appear on this list.