The first reference to Megatron as a former gladiator is in Transformers Annual 1986, part of the UK-exclusive Transformers comic book series published by Marvel. The issue features a prose story written by James Hill entitled "State Games". Set on prehistoric Cybertron, this story features Optimus Prime and Megatron as rival gladiators. (The Prime Minister represents the nation-state of Ikkon, and Megatron represents the city of Tarn.) After a civil war between Tarn and its rival city of Voss, Megatron unites the survivors against Ikkon, fighting under his banner as a Decepticon.

Simon Furman, who wrote most of Marvel's Transformers comics, must have remembered State Games. In 2002, he wrote the new comic miniseries Transformers: The War Within, another prequel set on Cybertron where Megatron was a former gladiator. ("War Within" was drawn by Don Figueroa and published by the now-defunct Dreamwave.)

The 2007 Megatron Origin comic (by Eric Holmes and Alex Milne) again showed Megatron as a gladiator, while adding to the idea that he was previously a low-class miner. This added a new nuance to the Decepticons: their fight was not only about conquest, but also about class revolution, especially since the Autobots were originally depicted as Cybertron's police force. So how did the Decepticons become imperialists while the Autobots became freedom fighters? It's a contradiction, I think only Transformers One has it squared away. (More on that soon.)

Due to constant reboots by different creators, the first two decades of Transformers are pretty scattered. It wasn't until the 2010s that parent company Hasbro began streamlining, character names and designs would be used more consistently, and each new Transformers series would have the same basic lore about who created the Transformers, why the war started, etc.

2010's Transformers: Prime was the first cartoon to bring many previously comic-exclusive features to animation, including Megatron's Gladiator storyline. "Prime" Megatron (re-voiced by OG Frank Welker) won over the crowd, leading the masses of the city-state of Kaon to a revolution against Cybertron's oppressive caste system. Of course, in the present, he's the same warlord as ever - 'cause all revolutions are corrupt, right?!

During Transformers: Prime, Megatron is shown to be very proud of his roots. In the episode "Crossfire", he is ambushed and imprisoned in a makeshift arena opposite powerful insecticon. However, he triumphs and after decapitating the bug, he exclaims, "Let that be a warning to anyone who dares cross Kaon's gladiator, be it Decepticon or Autobot!"

In the 2012 video game Transformers: Fall of Cybertron, Megatron finds himself back in the gladiator pits cutting down treacherous Decepticons led by the usurped Starscream. Megatron boasted that he had already proven his worthiness to lead in that same arena. "That day is long gone, Megatron," Starscream taunts, to which Megatron retorts, "That day will live forever!"