Companions
K-9 played by John Leeson (voice)

Also played by David Brierly (Season 17)

John Leeson (voice) as K-9
First regular appearance: The Invisible Enemy
Last regular appearance: Warriors' Gate

K-9 has also appeared in:

K-9 joined the TARDIS when his original owner, Professor Marius, was unable to bring him back to Earth due to luggage limits. K-9 was a robotic dog which functioned as a mobile computer/defence system.

K-9 Mk I stayed with Leela on Gallifrey, the Doctor produced a K-9 Mk II, which remained in E-Space with Romana.

K-9 Mk III was a gift from the Doctor to Sarah Jane Smith.

K-9 Mk IV was also a gift from the Doctor to Sarah Jane Smith when K-9 Mk III was destroyed in an explosion.

K-9 has met these regenerations of the Doctor:
Home (Mark I):
  • Bi-Al Foundation
Home (Mark II):
  • The TARDIS
Home (Mark III):
  • London, Earth (20th century)
Home (Mark IV):
  • London, Earth (21st century)