Manuel Mendoza

Private Manuel Mendoza was one of the Marines who survived the crash landing on Installation 04. He was the Marine that Sergant Avery Johnson loved to yell at. He was part of Fireteam Charlie, who were led by Captain Keyes to find the "weapon cache" that 'Qualomee had told them about. Instead, the so-called "cache" turned out to be the main holding area for the Flood, and all of their team, save for Sergeant Johnson were attacked and assimilated by the Flood, and turned into Flood Combat Forms. Mendoza attempted to escape the room, but became infected. The chief then shot Mendoza beause he was infected. In the book Halo: The Flood it says, the results were both spectacular and disgusting. As the corpselike horror came apart, the Chief saw that one of the small, spherical creatures had taken up residence inside the soldier's chest cavity, and seemed to have extended it's tentacles into other parts of what had been Mendoza's body" (pages 224, paragraph 6, lines 1-5)..

Trivia
There is also a glitch in Halo: Combat Evolved that allows you to get back on board the Pelican in the level 343 Guilty Spark. Once the Pelican lands, the player may run around the perimeter of the level, where Private Mendoza stands, surrounded by many dead combat floods in the area. Also by doing this, the player can skip most of the outdoor portion of the level. To do this, throw a grenade as the Pelican is landing and you will stay inside the ship. It will then crash some way away and you can explore the upper area of the level.