The Master Control is a program in the Omnitrix and its successors. It allows unlimited access to all of the Omnitrix's functions like access to all aliens in the watch and also, instant changes and no time limit in Back with a Vengeance.
The Master Control was first used in Back with a Vengeance. Ben unlocks it by accident when on a boat trip. When a man falls off the boat, Ben uses Ripjaws to get him out of the water, then Stinkfly to fly on back to the boat. He then stays Stinkfly for hours (showing off his unlimited timing) and ruins Gwen's ice cream, who's extremely annoyed by his new powers. After this, he ruins some pictures and causes more trouble until Vilgax and Kevin 11 come to steal the Omnitrix, until Grandpa Max sends them into the Null Void, with Vilgax trapping Diamondhead along with them. After a long chase, they finally get the Omnitrix until Gwen tricks them and gets the Omnitrix back. But Ben, who turned off the Master Control, accidentally transforms into Grey Matter and tries to turn back, but fails.
Ben 10: Alien Force
The Master Control reappears in War of the Worlds when Azmuth activates it by voice command to grant Ben all of the Master Control abilities from the original series as well as unlocking every single alien in the Omnitrix. He used aliens from the original series such as Way Big and Cannonbolt (as well as Wildmutt off-screen as confirmed by Dwayne McDuffie) and Murk Upchuck. After the Master Control was deactivated, these 4 aliens were appended to his Alien Force list of aliens. However, the Omnitrix still powered down when Cannonbolt rapidly depleted it of all of its power faster than it could recharge by turning several DNAliens back into humans from a distance. It is also revealed that he would still revert to human if knocked unconscious.
Ben 10: Ultimate Alien
The Master Control is unlocked in Inspector 13, this time on the Ultimatrix. It was activated via hacking when three firewalls were breached. Ben deactivated the Master Control setting at the end of the episode, when he reset the Ultimatrix to turn Gwen and Kevin back to normal.
- According to Dwayne McDuffie, Ben could activate the Master Control via Voice Command, but he'd have to unlock it manually first.
- Even though the names by which Ben calls his aliens are made up, the Omnitrix recognized them when the Master Control was unlocked.