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Well, I'm sorry. I'm not Tony Stark.
~ Riva to Obadiah Stane about making a suit similar to Stark's Arc Reactor.
William Ginter Riva is a recurring antagonist in the Marvel Cinematic Universe, serving as a minor antagonist in the 2008 film Iron Man, and later as the secondary antagonist of the 2019 film Spider-Man: Far From Home. He is a former Stark Industries scientist who was allied with Iron Monger and later Mysterio.
Riva started out as the head of a team of scientists working for Tony Stark, even developing a new set of Combat Drones for the company.
However, it was not until he was forced by Stane to make a suit for him similar to how Stark made his to defeat several members of the Ten Rings back in Afghanistan. Stane also commented that Stark has made a power source called the Arc Reactor and that he wants Riva to create a miniature version of it as well. However, Riva fearfully stated that he cannot do that because he is not of the same caliber as Stark's, much to Stane's fury. It eventually turns out that Stane betrayed Stark to the Ten Rings in order to take the company for himself and that Riva was involved in it the entire time.
Spider-Man: Far From Home
It was revealed that Riva was supposedly fired by Stark for his allegiance with Stane following the latter's death, and Riva became very embittered by this by vowing to get revenge on Stark for his dismissal. He is also outraged of the fact that Stark has become more popular as the latter sacrificed himself to destroy Thanos and the Black Order to save the universe. As such, Riva joined up with a group of former Stark Industries employees led by Quentin Beck, who formulates a plot to stage terrorist attacks around the world so that he can use his special illusion abilities (as Mysterio) to "foil" those attacks and usurp Stark as the world's greatest hero. As part of the plan, Riva used his combat drones that he previously created to project super-powered entities called the Elementals; even managing and maintaining the attack drones equipped with Mysterio's specialized illusion tech.
After the defeat of Molten Man in Prague and Spider-Man deciding to give up the E.D.I.T.H. glasses to Mysterio so that he can become the next Iron Man, Riva is shown celebrating with the rest of Mysterio's Crew over their success and holding a toast to Tony Stark. Later, Riva and the other crew members are shown preparing for the final Elemental attack in London, where Mysterio has the drones increase the damage they cause in order to further the illusion. During the preparations, Mysterio discovers that one of the drone is missing a projector, which Riva claims to have not told him about before due to dismissing it as a minor inconvenience, only for Mysterio to lash out and claim that the projector is evidence as to what they are doing and that Nick Fury will kill him if he finds out he was tricked, threatening to kill his entire crew to prove his point. Mysterio then tracks the projector using E.D.I.T.H. and finds it in the possession of Peter Parker and his classmate Michelle Jones (or MJ for short), angrily claiming to Riva that Peter's blood will now be on his hands.
Mysterio subsequently uses his illusions to trick Peter into telling him the names of everybody that he told about his plot—MJ, Ned Leeds and possibly Betty Brant—before seemingly killing him by leading him into a train, before proceeding with the final Elemental attack, with Riva guiding the drones and also sending some after Peter's friends. However, Spider-Man, with help from Happy Hogan, manages to destroy the illusion by electrocuting many of the drones, much to Mysterio's fury, resulting in him ordering Riva to fix the illusion while claiming people will see what he wants them to see. Unfortunately, Spider-Man overcomes the drones anyway and defeats Mysterio, who seemingly dies due to a misfired bullet. Despite this, Riva used recordings from the drones to doctor footage and release the altered events to news outlets exposing Spider-Man's true identity and framing him for the attacks. It's unknown what happened to Riva afterwards, but he has avenged his employer's death and it's likely he is still at large.