2009's cosmic crossover event War of Kings is noticeable for bringing two formidable Marvel combatants face to face: Rocket Raccoon, the weapons specialist of the Guardians of the Galaxy, and praetor of the Shi'ar Empire Kallark, better known to comic book fans as Gladiator. Gladiator has previously overpowered Earth's finest superhero forces, but it was the anthropomorphic Rocket who would ultimately bring down this godlike being.
Though Gladiator has a personal distaste of the current Shi'ar mutant ruler Gabriel Summers a.k.a. Vulcan, Gladiator's loyalty to his empire is the ultimate driving force of the feared commander. This loyalty to the Shi'ar has seen Gladiator himself take down armadas of star-ships, destroy planets, tear apart black holes, and even stun Thanos The Mad Titan, all with his Strontian acquired super strength, super speed, flight, heat vision, invulnerability, super breath, and accelerated healing. In terms of general abilities, Gladiator is the Marvel equivalent of DC Comics' chief hero Superman, albeit sporting purple skin and a mo-hawk. Apart from Rocket's Quantum Cannon, the only source of weakness holding Gladiator back is his level of confidence. If Gladiator loses his confidence, the being would be vulnerable to attacks from less capable adversaries.
Following an invasion of the Kree homeworld, the former majestrix of the Shi'ar Empire Lilandra has been taken hostage by Gladiator and the Shi'ar's Imperial Guard. With no one else to turn to, two groups of space misfits are called for help: The Starjammers, and the Guardians of the Galaxy. The Rocket Raccoon-led Guardians quickly confront Gladiator, with the Shi'ar praetor unaware of his pint-sized opponent's massive ace up his sleeve--giving Rocket ample time to strike the super-being with his handy Xarthian Quantum Cannon, temporarily immobilizing the Imperial Guard's figurehead, allowing the Guardians and Starjammers to completely focus on the mission at hand. However, Rocket's quantum cannon is revealed to be merely a telepathic assault brought on by Starjammers telepath Rachel Summers a.k.a. Marvel Girl to deceive Gladiator and his psionic fueled abilities.
As leader of the Shi'ar's Imperial Guard, Gladiator has found himself up against several Marvel heroes throughout the cosmos from the X-Men, Fantastic Four, and Thor, with each experiencing an immense amount of difficulty in defeating the Imperial Guard commander. Gladiator's early visit to the hub of all superhero activity Earth, in pursuit of the shape-shifting Skrulls, saw the alien traveler effortlessly lift the Fantastic Four's 35 story New York City headquarters The Baxter Building from the ground. It was Mr. Fantastic's quick thinking that saved the first family from feeling Gladiator's full wrath.
Similar to his battle with the Fantastic Four, it is Gladiator's confidence which gets the better of him in his memorable first battle with Rocket Raccoon. Though Rocket's cannon is revealed to be a telepathic illusion, Gladiator was kept at bay for an expanded period of time. Any other Marvel superhero would be lucky to keep the praetor down for a moment or two. Whether it is Rocket Raccoon or the entire Guardians of the Galaxy team, Gladiator will face any threat as a show of loyalty to his empire.