Ed Dillinger Sr.

Ed Dillinger Sr.  is the true main antagonist in Tron.

He was portrayed by David Warner, who also played the Master Control Program.

Overview
Ed Dillinger, Sr. is the president of ENCOM at the outset of the story. He only cares about his position and is determined to keep it. He also created the Master Control Program in order to ensure that he maintains control of ENCOM. His ultimate goal is to use the programming abilities of Space Paranoids (which was created by his former employee Kevin Flynn) to get rich. After the MCP was de-rezzed, Dillinger loses his job and presumably goes to jail.

Trivia

 * Although the Master Control Program is the main antagonist of the film, Dillinger is the true antagonist since he created the MCP and acts as his boss.