O'Brien (The Web of Fear)

Private O'Brien was a soldier in the British Army. He took part in the fight against the Great Intelligence and its Robot Yeti in the London Underground. While trying to collect ammo from a ambushed supply truck, a Yeti killed O'Brien with its web gun. (TV: The Web of Fear)

Behind the scenes
O'Brien is only named in the dialogue for episode two; he is credited as "Soldier" is the end credits.