Geoff

Biography
According to the E3 2000 demo, Geoff was serving on the Pillar of Autumn in 2552, which crash-landed on Halo. There, Geoff and the rest of his squad were to infiltrate a Covenant held bunker. Geoff and two of his squadmates drove there on a Warthog, Geoff riding shotgun, while the other three members got there on foot.

Geoff and the rest of the squad broke into the bunker, but lost Segure in the process. He and Wang were tasked with guarding the entrance door to the bunker. They failed in their attempt to help their sergeant, who was ambushed and killed. Geoff escaped in a Ghost, while Wang covered him. Followed by two ghosts and Banshees, his ghost got shot down, but he was saved in time by the Master Chief. The two of them were the only survivors of the mission.

He most likely died when Master Chief destroyed the Halo.

Trivia

 * The E3 2000 demo was shot while Bungie was still working on the game. some aspects of the demo there couldn't be canon. for instance, the master chief was in the demo, while in both Halo: Combat Evolved and Halo: The Flood there was never a mention of the Master Chief participating in such mission.