William Magnus is the Amalgam version of DC's William Magnus and Marvel's Bolivar Trask.
 
William Magnus is the brother of Erik Magnus, known to the world as Magneto. Jealous since childhood of his mutant brother, Will Magnus obsessively honed his robotics skills, culminating in the creation of the mutant-hating Sentinel robots. As a non-mutant, Will is determined to be the greater of the Magnus brothers, even if that means he has to be the only child! His grudge has expanded to include the entire mutant race. 
 
In addition to creating the Sentinels to wipe out the mutant race, Magnus also created a robotic 'wife' in the form of Jocasta, who was programmed to adore Magnus. He also built the ultimate mutant hunting sentinel, Sinistron. 
 
Magnus is responsible for creating Quasimodox, Chemodam, Kultron and possibly had a hand in creating the other members of the Sinister Society, who all come to blame Magnus for what he has done to them. In addition, Magnus created the synthetic man known as the Red Vision, who he planned to use as an insider in the Judgment League Avengers.

It was Will Magnus who played a factor in the Judgment League Avengers having dissension in their ranks, which led to formation of the team known as JLX. They were able to defeat Magnus and destroy many of his Sentinels, including Jocasta.

He formed a new base on Krakoa, the Living Dinosaur Island. He soon rebuilt Jocasta.
 

Magnus developed small machines known as Insectobots and built them by the billions. They are programmed to destroy everything they encounter, send him information and then die. This attracts the attention of his brother who traces him to the island. But Magneto does not pursue Magnus when he learns his Magnetic Men need his help. By the time they return, Magnus had escaped and left no trace of his operation.