Mark Ryan

Mark Ryan was a security guard assigned to the Mars City Underground. He guarded the airlock connecting it and the abandoned comm facility. After being told by Brooks that Doomguy was coming ahead of time, Ryan directed Doomguy towards the comm facility and assuaged his fears about having to walk around on the surface of Mars by reminding him that his suit carried plenty of oxygen. Unfortunately, at the start of the invasion, Ryan was killed by a zombie, who dragged him away and started eating him before Doomguy returned and promptly killed it.

The player can pick up Ryan's PDA if he shoots him when he first sees him. The only thing it contains is an e-mail from Brooks about Doomguy coming. He doesn't appear in the Xbox port, although his PDA can be found.