By Jim Beard
This past Sunday, the Avengers faced one of their greatest threats yet as Ultron rebelled against his masters and struck out at the team in "The Avengers: Earth's Mightiest Heroes!"
Now, before our heroes face the robotic villain once again this Sunday at 10:00 a.m. ET on Disney XD, we've got the maniacal mech Ultron's full comic book history! Catch a quick debrief before you witness the Avengers final battle with Ultron this weekend!