Ultron

Created by Hank Pym as an experiment in artificial intelligence, Ultron quickly developed self-awareness and turned violently against his creator, becoming one of the Avengers' most relentless and dangerous enemies. He continuously upgrades his robotic body, making himself nearly indestructible with each new incarnation.

Few villains in Marvel's long history have cast as long and dark a shadow as Ultron, who first menaced the pages of The Avengers #54 in 1968, conjured by the legendary team of Roy Thomas and John Buscema at the height of the Silver Age. Over nearly six decades of continuous publication — 209 catalog appearances and a remarkable ten key issues to his name — this relentless machine has proven himself one of Marvel's most enduring and essential antagonists. He haunts the same pages as Captain America, Iron Man, Thor, and Clint Barton, which tells you everything about the weight class he operates in: only Earth's mightiest heroes seem equal to the task of facing him. Whether tearing through Avengers storylines or surfacing in Marvel Super-Heroes Secret Wars, Ultron remains a cornerstone of Marvel's mythology — a character whose staying power across generations of readers is, frankly, extraordinary.