Other Dave

"Other Dave" was an engineer on the Felman Lux Corporation's expedition led by River Song and Strackman Lux to the Library in the 51st century.

Biography
He was called Other Dave since another crew member named Dave, nicknamed Proper Dave, had joined before him. (TV: Silence in the Library)

He was in charge of opening doors for escape routes when the expedition became trapped in the Library. He was charged with accompanying the Tenth Doctor in negotiating with the Vashta Nerada swarm that had taken over Proper Dave's suit and data ghost, but whilst the Doctor was reasoning with the creature, the swarm inhabited "Other Dave"'s suit and he was eaten, becoming like Proper Dave. He was returned to life in the computer core after CAL and Doctor Moon had saved him and the rest of the team. (TV: Forest of the Dead)