Thomas Parnell was a serial killer targeted by Skynet prior to Judgment Day. After being executed, he was obtained by Dr. Serena Kogan and placed in cryogenic storage to become Skynet's ultimate weapon in the future war against the Resistance.
Terminator Salvation: The Final Battle
Parnell was utilized as a human adaptation by skynet. This adaptation was intended to bring an individual with human killing capabilities to the battlefield. Eventually Skynet lost control and Parnell overpowerd Skynet and took control over the machines. He then utilized the Skynet assets to slaughter Conners battalions.