Mega-Doris is a huge hat-like robot and the tertiary antagonist of Meet the Robinsons. Despite his appearance, Mega-Doris is not actually a hat but rather a giant robot when Bowler Hat Guy alters Lewis' future.
Mega-Doris is (possibly) the largest model of the helping hats and a giant version of Doris that serves as a body that she can control. This form was present in the alternate future of Meet the Robinsons where Doris ruled the world replacing the Robinsons' original home. However, its use against Doris' original creator, Lewis, was short-lived when Lewis fixed the original time machine in time before he was cornered by the giant and prevented the alternate timeline from occurring, and she was wiped out from existence when Doris was erased.