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. (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.