Pvt. Miller was a human soldier of the Raze Task Force who served under the command of Sgt. Johnson and Cpt. Simmons. He was ranked a private, and was equipped with standard Mk.I Raze Soldier armor and basic weaponry. Private Miller served with the Player through many battles, and proved to be quite efficient. However, when the Zombie Virus was implemented aboard a cargo ship he and his squadmates were on, he was infected, along with Richards, Simmons, and Johnson. The Player had no choice but to kill the four of them, in order to save his own life. After the skirmish on the cargo ship, The Player was ordered to retrieve the corpses in order to resurrect the squad, but was only able to retrieve the body of Sergeant Johnson. Miller's and Richard's corpses were reanimated and helped in the effort to kill their former leader.
Miller is first seen when the Player arrives to assist the Squadron in the defense of the Toxic Facility, one of the Task Force's key power sources. Miller and Richards stuck together to combine their intermediate experience, and proved to be very helpful soldiers.
He is later seen when the Squadron arrives with backup to save the Player and Sergeant Johnson from the now infected city. After they wipe out most of the zombies in the area, they are evacuated from the war torn buildings.
Miller returns in the siege of an alien cargo ship after the Player loses his robot reinforcements. After hijacking the cargo, they board a ship of their own to transport it away.
Little to their knowledge, however, the aliens tracked down the cargo ship and implemented the virus into it. Miller and the Squadron manage to kill all of the zombies, but is infected shortly afterward. He was killed regretfully by the Player, but his body was later recovered by the alien remnant forces and reanimated.
Miller's final appearance is back in the toxic facility, where he participated in one of the two concurrent battles within the facility: the execution of Robo Johnson. Due to the virus inside of him, his efficiency in battle was gone and Private Miller was gunned down by Johnson early in the battle.