Iron Man, Thor, Hulk and more of Marvel’s greatest characters assemble for the first time in the series premiere two-parter of “The Avengers: Earth’s Mightiest Heroes” on Wednesday, October 20 at 8:30 p.m., ET/PT on Disney XD. Now, on a day like none other, prisons open wide, simultaneously releasing every single villain in a breakout unlike anything the world has never seen.  Our heroes’ only hope is to band together…to become the Avengers!