Fan CastingThe Master Doctor WHO Beyond

Like the Doctor, the Master would also flee from Gallifrey in a TARDIS of his own, and fully embrace his darker nature. The Master then went on to fight various battles against the Third Doctor and UNIT during the Doctor's exile on Earth, even spending a short period also trapped on the planet after his dematerialisation circuit was briefly stolen by the Doctor and when he was imprisoned on Fortress Islandafter being arrested by UNIT, until he was able to orchestrate his escape with the aid of the Sea Devilsread more