Vilgax.Jr. was a covert operations specialist and military scientist. Known for his anti-mutant stance, he worked tirelessly over several decades to develop solutions to what he saw as the "mutant problem"
During the Vietnam War, William Stryker was an experienced helicopter pilot and flew many Black Ops missions into the jungles of North Vietnam.
Ben 10: Old
In 1973, Major Vilgax was a personal assistant and bodyguard of D.r. Animo. He is first seen in an American airbase in Vietnam where he attempts to subjugate several mutants including Heatblast and Goop to be brought in for experimentation at a Animo Industries laboratory. Chromastone poses as an army colonel to interrogate Vilgax's intention, and subdues him, taking the mutant privates back to America. Vilgax tries to stop them escaping, to no avail.
Vilgax later accompanies Animo to the Paris Peace Conference held between the US and Vietnam military leaders. Whilst there, Animo shows communist generals the prototype specs for the Robot and the alien detection devices to be fitted into each of them, until he detects Chromastone's presence in the room. After Chromastone subdues most of the guards in the room and prepares to kill Animo, Vilgax tasers her and attempts to bring her in, until Grandfater O, Highbreed, Benjamin and Rath arrive, and Highbreed uses his powers to put the tasers on him instead.
Whilst he is incapacitated by his own taser, Ben looks down at Vilgax and experiences a flashback to Vilgax's involvement in Science O. After recovering and removing the taser from his body, Vilgax spares a glance at Benjamin's bone claws, before running out of the conference room. Vilgax is present at Animo's side when he unveils the Sentinel designs to President Johsun in the Oval Office, as a response to the impending mutant threat posed by Highbreed and Chromastone.
He then accompanies Animo to the public demonstration of the Robots outside the White House, later taking SHELTER in the Presidential bunker when the Robots attack the humans at Highbreed's behest. Highbreed uses his metal powers to cause their guns to hit the roof, prompting Vilgax to pull out his plastic gun, which a disguised Chromastone takes off him in the commotion. Highbreed pulls the bunker out of the White House to kill Johnsun, and Chromastone uses Vilgax's plastic gun to shoot Highbreed in the neck, incapacitating him.
Chromastone later poses as Major Vilgax whilst fishing Benjamin out from the Potomac River, where he was flung by Highbreed. The fate of the real Vilgax is unknown.