20 Insane MCU Moments Marvel Didn't Show

Joss Whedon always intended Ultron to be the villain for the first Avengers sequel. However, the maniacal robot's appearance and backstory could have very different. In one script, Ultron was created by the government to replace the Avengers, forcing the team to disband. Once Ultron turned on his creators, the Avengers would have to team up to stop him.

Because Ultron has had over a dozen designs in the comics, Whedon brainstormed which look would work best for the film. In the teaser trailer, Ultron looks almost identical to his comic book depiction. Whedon decided not to go with this look, worried it was too robotic (which is ironic). Instead, this look was repurposed for Ultron's drone army and Ultron himself was tweaked to look more expressive.

Another idea was for Ultron to have six arms, which is how he is sometimes depicted in the comics.

In the film's conclusion, the Avengers battle a vibranium-clad Ultron along with his robot army. In the fight, the horde was meant to merge with the villainous android so the Avengers would have to fight a Godzilla-sized Ultron. Spider-Man was going to appear during this fight but the idea ultimately fell through.