Sark

Sark is one of the main antagonists of the movie Tron and was the right-hand man of the MCP - a living embodiment of the MCP's will (more or less) and a ruthless tyrant who would do all in his power to prevent the hero of the story from attaining freedom.

Sark is distinguished by his cybernetic armor - which is colored red as opposed to blue - he also has great power over the virtual world and is also a very shrewd individual capable of plotting against his enemy.

Sark also appears as a boss in Kingdom Hearts - alongside MCP - where he gains the ability to grow considerably in size and power via linking with the MCP.