Mecha Mario is a fictional character in the Sprite Flash cartoon Super Mario Bros. Z. He is a robotic double of Mario built by Bowser's "secret assistant." He has so far appeared only once, briefly in the beginning of "Secret of the Pipe Maze". Mecha Mario's exact role in the series is currently unknown.
At some point prior to episode 7 Bowser met an scientist, most likely Dr. Eggman (though this hasn't been officially confirmed), who informs Bowser of the Chaos Emeralds. Bowser commissions two secret weapons from the doctor: the Omega Doomship and Mecha Mario. When Bowser learns that Mario is searching for the Chaos Emeralds, he decides to invade the Mushroom Kingdom and kidnap Princess Peach while Mario and his friends are away. Bowser then goes to check on the progress of his new weapons: although the Omega Doomship's defense system hasn't yet been installed, Mecha Mario appears to be fully functional.