Simon Stagg made his deput in 1965's The Brave and The Bold #57 from writer Bob Haney and artist Ramona Fradin.
Simon Stagg was outraged to learn that his daughter Sapphire was in a relationship with explorer Rex Mason, so Stagg sent Mason to Egypt to obtain the Orb of Ra. While in Egypt, Stagg ordered his bodyguard Java to beat mason to death. However, Mason survived and turned into a shape shifting hero known as Metamorpho after touching the Orb of Ra.
Major Story Arcs
Justice League Europe
Foxy Ladies/ Worm Food
When Stagg took over Jason Justin's company, Justin then used the Society of St. Cholmondely to destroy Stagg's factory in England. Stagg went to England to investigate the attacks and blamed the Justice League Europe for attacking his factory. Stagg was forced to retreat when a giant worm started to attack him.
Brightest Day: Outsiders
The Outsiders used a Markovian jet to fly to America, they were gunned down by Canadian jet fighters since they were passing the Canadian border. Stagg agreed to let the Outsiders stay at his Canadian estate just so he can rub it in Metamorpho's face while the Outsiders tried to prove they weren't a threat to the Canadian government. Stagg contacted the Canadian-American Embassy and an official from that place informed Stagg that since Markovia is still in the middle of a civil, the Outsiders are to be considered as war criminals. Black Lightning refused to believe Stagg's bad news and forced Stagg to find a way to get him and his team back to America. Stagg called in his new hired gun called Freight Train and Freight Train attacked Black Lightning, Owl Man, and Metamorpho. Stagg called off the attack when he felt that the Outsiders learned their lesson about disrespecting him.
Later that night, Java knocked Metamorpho out with the Orb of Ra and took him into Stagg's laboratory since he wanted to merge Metamorpho with Chemo. However, the experiment went horribly wrong and Chemo started to rampage Canada. Java contacted Freight Train to stop Chemo and Freight Train teamed up with the Outsiders to deal with the crisis. Freight Train was able to defeat Chemo by knocking its feet which caused Chemo to topple into a series of power lines. Chemo the vomited Metamorpho out since he became agitated by the electric surge. When the Outsiders returned to Stagg's estate, they found the Canadian Armed Forces waiting for them. Freight Train felt betrayed by Stagg and gave the Outsiders credit for taking down Chemo. The Canadian Government thanked the Outsiders for what they've done and allowed them to return to the United States.
Later on, Stagg had Freight Train kidnap Black Lightning so Black Lightning can use his electricity to help bring Sapphire back from the dead after merging the Black Lantern residue with some of Sapphire's DNA. Metamorpho and Sapphire were happy to be reunited, however Metamorpho wanted to kill Stagg for making him suffer for loosing Sapphire. However, Stagg left with Freight Train.
In Other Media
Beware The Batman
Simon Stagg was one of the richest industrialists who was kidnapped by Professor Pyg and Mr. Toad for participating in a shady land deal that destroyed protected wetlands. However, Stagg was saved because of Batman despite the fact that he was willing to let Alfred Pennyworth die after Alfred saved his life. Stagg later transformed Mason into Metamorpho since he was outraged that Sapphire was dating a security guard by luring him to a gas chamber while posing as an intruder and then testing an experiment on him that was called "Project Metamorpho". Batman discovered Stagg's involvement from a security footage and told Mason what happened which prompted Mason to attack Stagg at his company. Batman forced Stagg, who was fearing for his life, to help him cure Mason. However, the cure failed and Stagg tried to blame Batman for it, however Batman showed Sapphire a security footage that Stagg deleted of him turning Mason into Metamorpho. Stagg was then upset since he was going to get arrested instead of feeling guilty for his daughter's feelings. Batman later confronted Stagg in prison since he accused him of hiring thugs to wreck Old Gotham, however Stagg denied involvement even though he approved of people getting hurt and continued to plot a move to get back at Batman for doing nothing wrong that resulted in him going to prison.
Stagg appeared in "Metamorphosis" where he wanted to create the ultimate soldier referred to as Metamorpho for an oil company. Stagg had Java smuggle some chemicals into Gotham, however one of the chemicals leaked causing a train wreck to nearly happen until John Stewart arrived to save the day. Stagg was jealous of Rex Mason for dating his daughter Sapphire and turned him into Metamorpho by testing the chemicals on him. Stagg manipulated Metamorpho into attacking the Justice League, however Metamorpho went after Stagg after learning he was responsible. Stagg had Java use a cold gun on Metamorpho and tried to get his men dispose of him. However, Metamorpho broke free and attacked Stagg at his company. However, Staggs' mind ended up being transplanted into Chemo's mind and went on a wild rampage in Metropolis as a result of the attack. When Chemo was destroyed by Metamorpho, Stagg woke up in the hospital screaming.
Simon Stagg doesn't appear in Arrow, however he refused to sponsor Laurel Lance's law firm just so Laurel would face bankruptcy just so Laurel would sell the place to him. Fortunately, Tommy Merlyn stepped into save the day. One of Stagg's chemical plants where attacked by Firefly, however the Arrow put a stop to those attacks.
Stagg appeared in the "Fastest Man Alive" where he was targeted by Danton Black since Stagg stole his research which made Black unable to save his dying wife. When the Flash saved Stagg from Black, Stagg wanted to exploit his abilities just like what he did with Black's research and told Eobard Thawne about his plan. Fortunately, Eobard Thawne was able to stab Stagg to death with a knife he had hidden. Eobard Thawne later killed Mason Bridge the reporter in "Out of Time", since Bridge found out Eobard was the last person to see Stagg before he went missing.
DC Universe Online
Stagg sponsors animal killers which was why Cat Woman attacked Stagg Industries in the game.
Batman: Arkham Knight
Stagg arrived to Gotham City to do research on airborne inoculation technology and was accused of human right violations. Batman went to Founder's Island to look for Barbara Gordon who was abducted by the Arkham Knight. Batman took out the Arkham Knight's militia and Stagg told Batman that his company was developing a clean power cell technology and that Scarecrow was on the second airship. Stagg was working with Jonathan Crane, however Crane betrayed Stagg by using the fear toxin on him. Batman freed Stagg from his condition and threw him into another cell after borrowing one of Stagg's clean cell technologies.