K9
From Tardis Wiki, the free Doctor Who reference
K-9 was the first - and until Kamelion, the only - robotic companion to travel with the Doctor.
Biography
There were four K9s.
Mark I
See main article.
Mark II
See main article.
Mark III
K9 Mark III was built at some point by the Doctor (presumbably), which he left on Earth as a present for another companion, Sarah Jane Smith (K9 and Company). During the 1980s, K-9 Mark III still lived with Sarah Jane, but, by chance, would not accompany her to Gallifrey (DW: The Five Doctors). In early 2006, K-9 Mark III sacrificed itself to stop the Krillitanes. (DW: School Reuinion)
Mark IV
The K9 Mark IV was built by the Doctor to replace K9 MK III (DW: School Reunion).
