The Security Chief is a major antagonist in the Doctor Who story "The War Games".
He was portrayed by the late James Bree.
The Security Chief was one of the Aliens running the War Games, a plan to recruit an army of human soldiers to conquer the galaxy by kidnapping soldiers from Earth wars and brainwashing them into believing they were still fighting those wars. The Security Chief was stationed on the planet where the War Games were taking place, mainly to deal with resistance groups forming among soldiers who had broken their conditioning. He was subordinate to the War Chief, a renegade Time Lord, but highly suspicious of him, making it clear that his loyalty was to his people and their leader, the War Lord.
The Security Chief carried out an interrogation of Zoe when she was captured on infiltrating the control area, using a device that compelled the truth by threatening to damage the brain, and was stunned when she insisted she came from the 21st century, later than any of the processed humans. Learning of the Doctor and correctly guessing he was another Time Lord, the Security Chief enlisted the aid of the scientist to find out if there were any other unprocessed humans around. He was furious with one of his guards for letting Zoe escape, shaking the semi-conscious man.
The scientist sent Jamie to him on learning he hadn't been processed and the Security Chief unsuccessfully attempted to prove that the Doctor and his friends were working with the War Chief. Despite attempts to stop them, the Doctor and his allies escaped back to the war zones and took control of the chateau in the 1917 zone where the time zone controls were located. On the War Lord's instructions, the Security Chief led a raid on the chateau, recovering a processing machine the resistance had stolen and capturing the Doctor, who he unsuccessfully tried to interrogate.
When the resistance began a concerted attack on the Aliens posing as officers, the Security Chief sent more and more guards to investigate, leaving the control area with little defence. Having worked out that the resistance members were gathering in the American Civil War zone, the Security Chief wanted to wipe them out with a neutron bomb. The War Lord instead had the Doctor, who had pretended to switch sides, trick their leaders into coming to the control area where they were soon captured.
The War Lord gave the Doctor permission to attempt to reprocess the rebel leaders but the Security Chief deliberately left him alone with them, nearly resulting in him being killed. Having had the war room bugged, the Security Chief found a recording of the War Chief plotting with the Doctor to take over from the Aliens once the galaxy was conquered. He showed the recording to the War Lord and ordered both the Doctor and the War Chief arrested. However, the Doctor had already freed the rebel leaders and, with the War Chief, they launched an attack on the war room during which the Security Chief was killed by the War Chief.