The Raak

The Raak is a life form genetically-engineered by the scientist Crozier, on planet Thoros-Beta in the 24th century, to be at the service of the Mentors.

While it was programmed to be non-aggressive, a genetic regression caused it to revert to a savage state and attack the Sixth Doctor and Peri Brown without provocation.

Appearances

 * Doctor Who, season 23, "Mindwarp" (1986)