Despite becoming a major hero in many realities, Iron Man doesn't come from a purely heroic family. Tony Stark himself used to be a far crueler character, and even his father has recently been revealed to be connected to Mephisto. In a lot of ways, Tony's family has proven itself to be harmful on not just a personal level, but even occasionally on a global scale too. which makes a pretty good argument for them to be the worst family in the Marvel Universe.
Now, we're taking a closer look at Tony Stark's most evil relatives from across the Marvel multiverse to see just how cruel his family really can be.
MORGAN STARK
While Morgan Stark was Tony's daughter in the Marvel Cinematic Universe, the original Morgan Stark was the son of Edward Stark, Tony's paternal uncle, and he debuted in 1965's Tales of Suspense #88, by Al Hartley and Don Heck. Edward eventually left the world of business behind, which meant that Morgan didn't get the same access to the Stark fortune as his cousin Tony. Morgan grew to resent Tony and developed a gambling problem, eventually being forced to work against Tony to repay his debt. It didn't take much convincing however, as Morgan proved to be a consistently cruel figure. Morgan soon helped numerous other villains in their schemes against Iron Man, such as Count Nefaria, Madam Masque, Rumiko Fujikawa and even Norman Osborn during the events of Dark Reign.
Morgan once even took over a mercenary group of villains known as the Stockpile and controlled the robotic avatar known as Brass. Morgan eventually even briefly got the chance to become the newest version of Ultimo before being forced out of the advanced android. Morgan hasn't appeared much in recent years, however, there's always a chance he'll return to try and target his cousin once more.
GREGORY STARK
Introduced by Mark Millar and Carlos Pacheco in Ultimate Comics Avengers #2, Gregory Stark was the older twin brother of the Ultimate Universe version of Tony Stark. While Tony became world-famous even before becoming Iron Man, Gregory preferred to work from the shadows. He was eventually called upon by Nick Fury to help active "Project Avengers." After a series of events, however, Gregory found himself in a position of power within S.H.I.E.L.D. With Nick Fury on the run and both Tony Stark and Carol Danvers in critical condition, Gregory revealed that he'd actually manipulated the Ultimates and the Avengers against each other, which him access to the world defense apparatus and allowed him to create a brand new world order.
His plan led to revolts around the world, and he defeated many of the Ultimate Avengers with a newly revealed nanite swarm in his body that gave him powers. He was even able to briefly wield Mjolnir. When his conspiracy is uncovered, the Avengers and the Ultimates are able to put their differences aside and attack him. In the end, Tony is able to disable the nanites within him - reverting him to a mortal status just in time for Thor to hit him directly with a lightning bolt.
ARNO STARK
There are two versions of Arno Stark in the history of the core Marvel Universe. The first version of Arno is an alternate reality character who debuted in Tom DeFalco and Herb Trimpe's Machine Man #2 and was the son of Morgan Stark. After the disappearance of Tony, Arno ended up inheriting Stark Industries, which meant that he also gained access to the Iron Man technology his uncle Tony had once used to protect the world. Arno quickly used that tech to become a deadly mercenary.
Although he traveled back in time to stop a bomb from killing his family, Arno ended up appearing very much like a villain, leading Spider-Man to confront him and stall him for too long. By the time Arno returned to his time period, he was too late to prevent the bomb from going off and killing his loved ones. Since then, Iron Man 2020 has since appeared in various other reality-crossing storylines.
The modern incarnation of Arno is the biological son of Howard and Maria Stark and Tony's adopted brother. After spending most of his life in isolation to contend with a lethal disease, Arno and Tony quickly became close and worked on new projects together such as the futuristic utopia known as Troy. They were even able to figure out how to treat Arno's disease. However, Arno has become more fierce and relentless since he was awakened.
He eventually joined up with Sunset Bain and set himself up as the defender of the world from a mysterious technological threat coming from space. Arno even took the opportunity of Tony's apparent death during Civil War II to decry the replica of Tony that had been made and take control of Stark Unlimited. Arno has been at the center of the Iron Man 2020 event, even seemingly killing the copy of Tony in battle during his attempts to overtake control of all robotics across the Earth.