Gantok

Gantok was a humanoid who worked for the Silence, and was known to be their 'weakest link'.

Biography
Gantok wore Viking-style attire, along with the Eye Drive worn by many servants of the Silence. He was an avid player of Live Chess. He was proud of his skill at the game and, when the Doctor had beaten him during a match, Gantok offered to pay anything to escape. He told the Doctor that Dorium Maldovar knew many things about his death. Gantok helped him get into the Seventh Transept, where he turned on the Doctor, angry at him for beating him at Live Chess. He was killed when he stepped on a booby trap that dropped him into a pit filled with the skulls from the Headless Monks, which proceeded to devour him. (DW: The Wedding of River Song)

Behind the scenes

 * Counting spitfire pilot "Danny Boy", for whom Gatiss only provided only the voice, Gantok is the third character to be played by Doctor Who writer Mark Gatiss, the other being Professor Richard Lazarus. Mark Gatiss is not credited in The Wedding of River Song under his own name, but as Rondo Haxton, a reference to actor Rondo Hatton, on whom Gantok's acromegalic facial features seem to be based.