Sark is a program that appears in the film Tron and related video games. He is a program that was created by Ed Dillinger, the CEO of ENCOM that rose to his position after stealing coworker Kevin Flynn's video game designs and claiming the credit for himself.
Sark is the lieutenant of the Master Control Program. He follows the MCP's orders to establish control over ENCOM's systems and hunt down both Tron and the digitized form of Flynn. However, he is defeated toward the end of the film and is deleted.
In Video Games
Kingdom Hearts II
After Sora, Donald and Goofy are transported into the world of Space Paranoids in Kingdom Hearts II, the general plot of the game follows the basic story beats of the film Tron. As such, Sark serves as a major antagonist in Space Paranoids and stands in the way to prevent Sora and company from interrupting the MCP's schemes. Though the MCP gives Sark more power, he is ultimately defeated by Sora.