He is the Master Control Program's guardian and second in command, who overviews the arrested programs and forces them to play life-threatening games, at which the loser is immediately de-rezzed. When Flynn arrives, he is subjugated by Sark and arrested along the other programs, meeting Tron in the process. After chasing the heroes, he battles Tron at Central Computer Mesa, the Master Control's fortress.
Tron ends up defeating Sark and destroys his disk. However, the MCP revives him, and as Sark stood up, his size increased to a colossal scale. As Sark was made from the Master Control's data, he is de-rezzed along with his master when Flynn sacrifices himself.
Sark and the Master Control Program are the main antagonists of Space Paranoids. Sark has been made a Heartless commander by the MCP, empowering him even more. Not much of Sark is heard of after his first appearance, where he begins to de-rez Donald and Goofy in front of Sora, and imprisons the three in the Pit Cell. Not long after their imprisonment, Sark is called up by the MCP and suggests that Tron be de-resoluted, but the MCP wants to keep Tron because the latter has access to the password of the DTD database.
His second appearance is at the boss battle against the MCP. Strangely enough, despite having met before, here Sora cannot remember Sark's name until Tron refreshes him. The normal Sark is fought, along with his Identity Disk. Weakened, he tells Tron that they could have made a great team, but Tron flings his Identity Disk at him and knocks him unconscious, as he is more or less a program, and programs can't be killed, only deleted.
Not long after, the MCP revives him and grants all his functions to him, causing him to enlarge. He is a second-hand enemy as his giant-self while you fight the MCP. Like the movie, Sark is defeated along with the MCP, being de-rezzed.
Originally Sark and all of the villains were going to be blue. This was changed during production.