CLU was a hacker program created by his User, Kevin Flynn, and is, thus, identical in appearance, although he spoke in a different voice. In 1982, Flynn utilized CLU to hack the ENCOM mainframe in an attempt to find evidence of Ed Dillinger's fraud. Dillinger had stolen credit for video games Flynn had created for ENCOM, allowing him to Senior Executive of the company. While searching the system in a tank, Recognizers are alerted of his presence, and begin pursuit. CLU manages to destroy several Recognizers, but is ambushed while escaping. While CLU manages to destroy the attacking Recognizer, his tank is struck by debris, sending it out of control and into a wall. More Recognizers arrive as CLU tries to escape the tank, capturing him.
CLU is taken to the Master Control Program (MCP), who interrogates him. After being thrown onto a torture device, Clu defiantly shouts, "Forget it, Mister High-and-Mighty Master Control! You aren't making me talk." CLU is then derezzed by the MCP, who takes away his functions.
- Main article: CLU 2.0
Shortly after his death, CLU's user, Flynn, is digitized into the system and takes over where CLU left off, eventually succeeding in bringing freedom to the system and exposing Dillinger as a fraud with the help of Tron, Ram, and Yori. Flynn is then made CEO of ENCOM.
Kevin Flynn created CLU to oversee the development of the Grid and who becomes the main antagonist of Tron: Legacy. He is played by Jeff Bridges.
CLU was created by Flynn to oversee the development of the Grid, so that Flynn could make time in the "real world" as CEO of ENCOM and for his son, Sam. Programmed with the command of creating a perfect system, CLU grew to resent Flynn as his actions took him further away from CLU's idea of perfection. After the manifestation of the ISOs, unique life forms which CLU saw as imperfect beings, CLU became corrupted and betrayed Flynn and Tron to seize total control of the Grid, and then proceeded to enact genocide upon the ISOs, leaving Flynn to remain in the computer world for the next 20 years.
Over the next twenty years, CLU kept the Grid in a stranglehold as he sought perfection, reprogramming damaged or rogue programs as soldiers for his own army, led by a reprogrammed Tron under the name 'Rinzler'. He continued to seek Flynn for his identity disc, which possessed information that would allow CLU to cross over into the real world with his army so that they can perfect it in their own image. Eventually, he found a way to send a page to Alan Bradley, which led to Flynn's son, Sam, coming to the Grid. After first trying to destroy him, CLU attempts to use Sam to draw out Flynn, and succeeds in obtaining his identity disc.
After preparing his army, CLU advances the portal to the real world, but is unsuccessful after Sam, Flynn and Quorra steal back the disc, and Rinzler betrays him after learning of his past identity as Tron. In a last ditch effort, CLU attempts to take the disc from Flynn on his own at the portal's gateway, but is tricked into stealing Quorra's disc, while Sam and Quorra keeps hold of Flynn's actual disc. Desperately trying to reach the portal as Sam and Quorra escape, CLU is ultimately destroyed as Flynn 'reintegrates' CLU into himself, resulting in an explosion that kills them both.