Manuel Mendoza

Crash-landing on Halo
Private Manuel Mendoza was one of the Marines stationed on the Pillar of Autumn, when it was attacked by the Covenant. After boarding a lifeboat, he survived the crash landing on Installation 04. He was the Marine that Sergeant Avery Johnson loved to holler at. During the events of the crash landing, he fought alongside the Master Chief, until he was evacuated by Echo 419.

Encounter with the Flood
Later on, he was part of Fireteam Charlie, which was led by Captain Keyes, to find a Covenant weapons cache that a captured Elite, 'Qualomee, had uncovered to them. Instead, the so-called "cache" turned out to be a Flood Containment Facility. The entire fireteam was immediately ambushed and, save for Sergeant Johnson, was assimilated into the Flood, and turned into Flood Combat Forms. As Mendoza fired at Infection Forms inside the Flood-holding chambers, he became infected.

A few hours after infection, Mendoza took an entire 8-gauge shotgun shell from the Chief's M90, with the results both spectacular and disgusting. As the corpse-like 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 used to have been Mendoza's body".

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 alone. 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. Here you can encounter an NPC skin of Mendoza, which will respond when attacked and is capable of being killed.