Rangorr was a Brainleader of the Kreech. He wanted to find an intelligent mind to take his place so that he could leave his responsibilities for the colony and go travelling amongst the stars.
Rangoor believed he had found a replacement when the Eleventh Doctor was captured. However, the Doctor escaped during a contest to find the cleverest. He left whilst Rangoor was distracted by a crossword puzzle. (COMIC: The Cleverest King)