K9 Mark II


 * Not to be confused with K9 Mark 2, a reincarnation of K9 Mark I that came to reside in 2050 London with Starkey in Professor Alistair Gryffen's mansion.

K9 Mark II was the second K9 based on a robot originally built by Professor Marius, though constructed by the Doctor.

History
Mark II was constructed as a replacement for the Doctor after Mark I, decided to stay on Gallifrey with Leela. The Doctor appeared to have prepared for the possibility of losing Mark I, as he already had Mark II (or at least its components) prepared and in storage. (DW: The Invasion of Time)

This version of K9 accompanied the Doctor and new companion on their quest to locate the segments of the Key to Time (DW: The Ribos Operation), however the swampy terrain of Delta III made it impossible for him to accompany them there. At the conclusion of the quest, the Shadow turned K9 to his evil will, during which time K9 assumed a sinister personality. (DW: The Armageddon Factor)

The Doctor found that K9 had contracted laryngitis and had lost his voice as a result of this. K9 was left in the TARDIS while the Doctor and Romana battled the Daleks and Davros (DW: Destiny of the Daleks). During a subsequent adventure, it remained patiently in the TARDIS, which would imply that his voice had not yet returned. (DW: City of Death) After the return of his voice, it sounded quite different and remained so for a number of adventures (DW: The Creature from the Pit). However, later the familiar voice returned. (DW: The Leisure Hive)

In E-space K9 commanded the attack on the castle of the Three Who Rule. He shot many of the guards doing most of the work. The Doctor made Ivo apologise to him for his harsh words. (DW: State of Decay)

Damaged by the time winds, K9 Mark II could not cross back into N-Space with the Doctor, so decided to stay behind at the Gateway with Romana, to help her free the remaining Tharils from slavery. (DW: Warriors' Gate) The Doctor, meanwhile, chose not to replace K9 again, though he did build/obtain a Mark III that he gifted to Sarah Jane Smith (KAC: A Girl's Best Friend) and apparently at one point also created a Mark IV that was also gifted to Smith upon the destruction of Mark III. (DW: School Reunion)

As for Mark II, he was later repaired, and accompanied Romana when she returned to N-Space. During Romana's term as President of Gallifrey, K9 Mark II served as her aide and advisor. (NA: Lungbarrow) He may have also shared an adventure with Romana and later incarnation of the Doctor at some point after this (WC: Shada)

What ultimately became of K9 Mark II is unknown, as he is no longer present during events before and after the arrival of Pandora (BFG: Gallifrey) or the events of The War which resulted in Romana regenerating into a third incarnation (EDA: The Shadows of Avalon).

Features
After K9 Mark I was left behind with Leela on Gallifrey, The Doctor built an improved K9 Mark II. While the cosmetic changes were minimal (including the new metallic charcoal paint-work), in terms of series continuity K9's character underwent a vast change. Gone was the product of 5000 AD technology, as was the case with Marius's version. This new K9 was a product of the Doctor's own technology and values. The gun was now only capable of stunning - not killing - and K9 now responded to a dog-whistle. K9 also featured a vast memory-bank, seemingly a mixture of the Mark One model, the Doctor's own memory and knowledge, and that of the TARDIS. (DW: The Invasion of Time)

Production notes

 * The production team used the same prop for Mark II as they had for K9 Mark I.
 * In WC: Shada, K9 mentions that Earth's soil interfered with his traction (a joke on the original prop's difficulty travelling in a straight line).

Casting
While John Leeson provided K9 Mark II's stories in all his other appearances, another actor, David Brierley voiced him in The Creature from the Pit, Nightmare of Eden and The Horns of Nimon. Leeson took over the role again from The Leisure Hive onward.