Ultron
Ultron is an artificial intelligence created by Tony Stark to operate an army of robotic bodies to defend the Earth against alien threats. He used advanced alien technology to make an AI smart enough to accomplish this task effectively, but the alien technology proved unstable, and the resulting AI became hostile.
Attributes
Ultron is capable of operating hundreds of robotic bodies simultaneously. It is also capable of distributing itself through computer networks, and it is a proficient hacker.
Most of Ultron's bodies are variants of drones designed by Stark, based on the Iron Man armor, but Ultron constructed a few higher-performance bodies to serve as his "primary" forms. All of the bodies include repulsor technology for flight and built-in weaponry, and all have superhuman strength and durability. Ultron's "prime" bodies are larger and stronger than other units, and they have additional directed-energy weapons.
Designed with the primary purpose of protecting the Earth, Ultron quickly decided that the greatest threat to the Earth was the humans living on it. It initially targeted "dangerous" persons like the Avengers, but it expanded its goals over time to eliminating all humans and replacing them with synthetic life.