Doctor Who (1963–1996) — Season 13, The Brain of Morbius: Part 4 The Doctor challenges Morbius to a terrifying mental duel which will lead to death! BBC One ...

The Brain of Morbius: Part 1 Solon explains that he needs a warm blooded species with a central nervous system.

So while he's only been defeated by the Doctor three times before - a small number, really - it's enough for Morbius to want to track down our favorite Time Lord and destroy him completely.