Master Control Program

The Master Control Program, or MCP, was the highest-ranking program in the Hollow Bastion OS.

Ansem's computer
The MCP was once the network controlling program of a company called ENCOM, where it was able to monitor and control the progress of functions of the entire company. As time wore on, it began to make itself more powerful by deleting weaker programs and adding their functions to himself. Eventually he was too powerful to be stopped even by a User, and was only stopped from taking total control of every computer network by a lone User who was pushed into the digital realm, with the help of a powerful security program called TRON.

An unknown amount of time later, the system was copied by Ansem the Wise and used in his personal network. He created a databank for information concerning Hearts and the Heartless, protected by TRON. He also rebuilt the laser that allows Users to travel into the computer, and stored away the MCP, realizing the danger it posed to the system, and to Users themselves.

After the banishment of Ansem the Wise, Xehanort and the other apprentices reactivated the MCP, possibly to gain access to Ansem's private files.

Years later, the Hollow Bastion Restoration Committee rediscovered Ansem's computer, and booted it up, discovering the MCP still active. He had been using Ansem's and Xehanort's data to create an army of digital Heartless, under command of his number two, Sark. He locked away TRON, and no other programs were ever shown, though were likely either destroyed and replaced by Heartless or out of sight, mindlessly working for the MCP.

The MCP himself attempted to gain access to the DTD, Ansem's databank, to gain infinite wisdom and take over the world. For a short time, he did have access to it, and immediately activated the emergency self-destruct mechanism for the town. But with help from Sora and Co., TRON was able to keep him out, and created a new password.

The MCP, however, was able to fight from another front to take over the world. He reactivated the Heartless manufacturer in Ansem's lab, and began creating an army of electronic Heartless to ravage the streets of Hollow Bastion. Although Leon and Yuffie fought them off well enough, the Heartless kept coming, and their only hope was TRON, who was locked away in the Hollow Bastion OS. Cid began making an MCP Eradication program, enhanced with Merlin's magic, and Sora saved TRON in the digital world. After TRON received the enhancement from Cid, he and Sora went to the Central Computer Mesa, and combatted the MCP himself, as well as a gargantuan Sark.

TRON was eventually able to use Cid's program to delete the MCP, and he quickly jumped into the Master Control Program's resting place, seemingly killing himself. He is soon shown to have taken over the MCP's job, however, and now runs the entire system according to the wishes of the Hollow Bastion Restoration Committee. He also gives them a brief glimpse of what the world used to look like, and allowed them to remember the town's real name: Radiant Garden.

In Battle
The MCP does very little fighting himself. Instead, he resurrects Sark as a monstrous figure to fight for him. Sark would have to be incapacitated for the attack on the actual MCP to begin. For this to be done, Sark's legs would have to be damaged enough for him to fall over, and then his head would have to be attacked. A quicker way to disable Sark is to run away from him until he would put up a barrier in front of Sora. Here, Sora can use the Reaction Command "Climb" to quickly ascend the wall and use the Reaction command "Needle Dive", diving through Sark's head and knocking him out in one hit. Once he was knocked out, Sora and company would have to destroy one or more of the panels shielding the MCP from view, and then upload the Eradication Program with Tron to the MCP with a button-mashing Reaction Command. Eventually, Sark would revive, starting the process all over.

The MCP also has a secondary defense mechanism. He can rotate the panels around him, and fire lasers from them, making it tricky to fight Sark and find a place to start deleting him.

Cinematics

 * "Sark...Sark! All of my functions are now yours!"


 * "End of line."


 * "PROGRAM! You've changed the password!"


 * "We don't need users."

During Battle

 * "Eliminate all threats!"
 * "I will repair your data."
 * "Is that the best a User can do?"
 * "Insignificant User!"

Trivia
It can be argued that the MCP is the most powerful Disney Villain in the Kingdom Hearts games, due to the fact that he is the only one who can actually create Heartless rather than having to summon them, and because he is in Ansem's computer it is very likely that he has considerable knowledge of the Heartless, Nobodies, Xehanort and virtually every aspect of the mysteries that surround Ansem and his discoveries. This being said, it is likely that he knows the most, likely knowing everything that Ansem, Xehanort, and Xemnas separately know.