This page lists appearances of K9 Mark IV in the order in which he experienced them. This timeline is based on observations of the Doctor Who universe and the events in each of these stories. From these observations we have attempted to build a concise timeline. It is assumed, much like their TV story counterparts, that each novel or audio series their published/numbered order is the order they occur in.
The layout of this timeline is based in part on the observations on Doctor Who Reference Guide and Doctor Who - The Complete Adventures, Lance Parkin's AHistory and other sources that allow us to make observations, such as DocOhoReviews, The History of the Doctor, The Discontinuity Guide, Clive Banks Databank, the Big Finish forums and The Divergent Universe forums. None of these sources should be used solely as a source or considered a "true" timeline for stories.
- At some point, K9 Mark IV is constructed by the Doctor at some point after his fourth incarnation left K9 Mark III to Sarah Jane Smith. (PROSE: Just a Small Problem, TV: A Girl's Best Friend) Though he is not unveiled until the Tenth Doctor leaves him, (TV: School Reunion) a comment made by the Eighth Doctor suggests that Mark IV had been constructed as early as his time. (PROSE: Interference - Book Two)
- Set in 2007. K9 Mark IV is left to Sarah Jane as a gift from the Tenth Doctor following the destruction of K9 Mark III. K9 claims that he has been "rebuilt", acknowledging the loss of his predecessor.
- Set in 2008. K9 briefly talks with Sarah Jane from space. He has been working on the black hole for a year and a half.
- K9 briefly leaves the black hole to fight Mr Smith.
- K9 briefly leaves the black hole to intercept a Slitheen.
- K9 is present at Sarah Jane's funeral. He leaves with Ace.