Gibbis

Gibbis was a native of Tivoli, a grey planet whose residents took a strange delight in subjugation.

Biography
Before he was plucked from Tivoli and locked into the Minotaur's prison, Gibbis worked in town planning. He was engaged in a project to line all his planet's highways with trees so that invading armies could march in the shade. (DW: The God Complex)

Personality
He was a coward, a trait of Gibbis' species, the Eleventh Doctor described it as an aggressive sort of timidity. Gibbis was prepared to sacrifice Howie in the name of self-protection and showed a sadistic pleasure in unnerving Amy when he suggested she might have not yet have entered 'her room'. (DW: The God Complex)