Private Peter O'Neal is a member of the military branch USCM (United States Colonial Marines) who is a part of a search and rescue team sent to the Zeta II Reticuli system aboard the USS Sephora to investigate the USS Sulaco in search of Ellen Ripley, Corporal Dwayne Hicks, and the rest of the missing marines who were dispatched to LV-426 19 weeks earlier.
O'Neal was born and raised in Newark, New Jersey and was recruited by the USCM in 2177. He ranked top of boot camp training class. He is a top gunner, an expert in long distance projectiles, follows command and remain calm even while under pressure. He was dispatched to O'Niell Station, L-4 Earth-Lunar System in 2178. During his first mission, his squad took heavy fire on the USS Sulaco. O'Neal was the only survivor. The USCM recommended him for First Responder Squad, front lines detail. In the game, O'Neal is closed friends with Bella.