Security guard (The Time of Angels)

A security guard was a member of Alistair's security staff on board the Byzantium Starliner. When River Song infiltrated the ship, she used her hallucinogenic lipstick to make the guard think he was in a forest. He was later found by Alistair, who wiped lipstick from his face, revealing it to be the calling card of River Song. He is thought to have been killed when the Weeping Angel crashed the Byzantium. (TV: The Time of Angels)

Behind the scenes
In the non-narrative based reference book The Brilliant Book 2011, his name was given as Josh.