Master Control Program
The Master Control Program is an administration program in the Hollow Bastion OS. He appears in Kingdom Hearts II as the highest-ranking program in Space Paranoids, and is the major antagonist of that world, bent on taking over the user world. He originated in Disney's 1982 film Tron.
Between Kingdom Hearts Birth by Sleep and Kingdom Hearts
The MCP was once part of a computer system for a company called ENCOM, along with Sark and Tron. That system was deleted and its contents became The Grid; however, Ansem the Wise discovered the old system at some point and copied it for his personal network. He created a dataspace for information concerning hearts and the Heartless, and used Tron to protect it. He also rebuilt the laser that allows Users to travel into the computer, and stored away the MCP, realizing the danger he poses to the system, and to Users themselves.
For reasons unknown, Terra-Xehanort and the other apprentices reactivate the MCP after banishing Ansem the Wise.
Kingdom Hearts II
Years later, the Hollow Bastion Restoration Committee rediscover Ansem's computer and boot it up, discovering the MCP still active. The MCP then locks away Tron, uses Ansem's and Xehanort's data to create an army of digital Heartless, and puts them under command of his number two, Sark. The MCP himself attempts to gain access to the DTD, Ansem's dataspace, to acquire infinite knowledge and take over the world; however, he is unable to access it without Ansem's password.
While attempting to access it, he is alerted to misuse of the physical computer in the User world, while Sora, Donald Duck, and Stitch manhandle the keyboard. After violating his ultimatum to handle the computer more properly, the MCP activates the laser and forces Sora, Donald, and Goofy into Space Paranoids, locking them in a pit cell with Tron. Having done so, he contacts Sark and briefly discusses the DTD, stating his refusal to de-resolute Tron until the dataspace is opened. An alarm sounds, prompting the MCP to task Sark with eliminating anomalies in the system and ends the conversation.
Meanwhile, Sora discovers Ansem's password and has Tron enter it, unlocking the dataspace. The MCP uses this opening to access the DTD for a short time and immediately activates the emergency self-destruct mechanism in Radiant Garden. With Sora's help, Tron is able to create a new password, locking the MCP out. In retaliation, the MCP attempts to upload a Hostile Program through the I/O Tower to attack the town instead, briefly taunting Tron before sending it into to fight, but this too is defeated by Sora and Tron.
The MCP, however, is able to fight from another front to take over the world. Seizing Tron once more and forcing him onto the Game Grid to fight for his life, he reactivates the Heartless manufacturer in Ansem's lab and begins creating an army of electronic Heartless to ravage the streets of Hollow Bastion. Leon and Yuffie fight off the Heartless to protect the town while Cid begins making an MCP Eradication program, enhanced with Merlin's magic. Sora and Co. re-enter Space Paranoids to free Tron from the MCP's hold and help him to the I/O Tower to receive Cid's program, then accompany him to the Central Computer Mesa to fight the MCP himself.
When Tron defeats Sark on the Mesa, the MCP transfers his functions to his lieutenant, enlarging him. Sora and Tron defeat the enlarged Sark and use the Eradication program on the MCP's base. The MCP tries to convince Tron that they can work together without the help of the Users, but Tron retaliates and deletes the MCP. Tron then jumps into the pit where the MCP once resided and takes over the MCP's functions in the Hollow Bastion OS.
Kingdom Hearts 3D: Dream Drop Distance
The Master Control Program appears in two forms over the course of Kingdom Hearts II. He first appears in a wire-frame form. This form is comprised of white lines forming a polygon mesh of triangles and quadrilaterals. It creates the silhouette of a human face stretched horizontally, with a large nose and wide mouth. The MCP's eyes are red pinpoints in this form.
The MCP's second form, his true form, is comprised of two massive, red cylinders that are being projected from a very small, spherical device between the two. This device is mostly silver with a red, circular light displayed on it. The light is surrounded by four black triangles. The bottom cylinder is featureless, while the upper one sports the MCP's face. Like in his wire-frame form, the MCP's face in this form resembles a human male's, albeit stretched across the cylinder. He has wide lips and a large nose, complete with nostrils, as well as faint "eyebrows". The MCP's sclera in this form are maroon, while his eyes are white. Only the first form is viewable in Jiminy's Journal.
The MCP's exact functions as controller of the Hollow Bastion OS are unstated. In Ansem's lab, he is able to monitor the main console, change the display on the monitors, activate the digitization laser, and run the Heartless Manufacturer; he also has access to the Claymore defense systems in the town. Within Space Paranoids, he can command Heartless, deploy hostile programs, and monitor and project his voice to multiple locations. He has also been shown to appropriate functions from other programs, such as Tron, or share his own functions with others.
The MCP does very little fighting, leaving that to Sark and the Heartless. However, he is able to summon defensive panels around his base, rotate them, and fire lasers from them.
The Master Control Program originates from the 1982 Disney film Tron, voiced by David Warner. Created as a chess program, the MCP was repurposed by Ed Dillinger (also played by Warner) to administer the entire system at the company ENCOM, a software manufacture and computer experimentation company of which Dillinger had recently become a high-ranking executive. The MCP began to expand beyond the control of Dillinger, blackmailing him with the evidence that he had gotten his promotion by stealing the video game programs of his coworker Kevin Flynn, and intended to hack the Pentagon and the Kremlin to replace human control of the world.
When Kevin Flynn attempts to hack into ENCOM's memory to retrieve the same evidence, the MCP digitizes him using an experimental laser, and locks him away with other programs he had captured to be eventually eliminated playing video games. Flynn meets Tron in the games, and together they escape the MCP and make their way to him. The MCP puts increasing pressure on Sark, his enforcer on the Game Grid, to capture Tron.
En route to delivering some elderly programs to be absorbed by the MCP, Sark finally captures the group. Leaving them on the ship as the MCP derezzes it, the group escapes and makes their way to the MCP's mesa. Tron defeats Sark, but the MCP transfers all of his functions to his enforcer, resurrecting him as a giant in a final bid to stop them. Unexpectedly, however, Flynn throws himself into the MCP, distracting the program long enough for Tron to erase. The MCP dwindles down to his original form, before disappearing for good.