Cortex Reaver

The Cortex Reaver is an enemy encountered in System Shock, both within Citadel Station and its Cyberspace.

Overview
Unlike most CyberSpace watchdogs, the Cyber Cortex Reaver is not a security program. Instead, it is a Net-active Cyborg whose awareness is constantly split between the physical realm (RealSpace) and CyberSpace. Reaver's intelligence is driven by the brain of an involuntary human puppet, using their dead body. Cyber Cortex Reavers are capable of quickly frying a user’s link integrity and withstand numerous attacks before crashing. Their Cyber forms are red, fragmented faces.

The Hacker first encounters one on the Flight Deck, while attempting to rescue a small squad of the Resistance survivors.

Strategy
Unsurprisingly, its physical version can be killed fairly easily with the Laser Rapier.

Trivia
However, in this case the background music doesn't stop playing until the game quits to main menu.
 * If the Hacker is killed and doesn't have access to a Restoration Bay, his fate is revealed in the "Game Over" cutscene. In it, the Hacker's head is inserted into a Cortex Reaver's chamber and brainwashed to serve SHODAN.
 * This also happens if the time limit runs out on the maximum Mission difficulty.
 * In System Shock 3 's teaser released by OtherSide Entertainment, the Cortex Reaver can be seen a few times during the video.