One of the most notable parts of Invincible was its hyper-violent style, distinguishing itself from Marvel and DC with comics every bit as brutal and bloody as their super-powered psychopaths should necessitate. And it only stands to reason that Invincible's strongest most psychopathic character of all would stand out as its most brutal.
Since he was introduced in Robert Kirkman and Ryan Ottley's Invincible #11 in 2004, Grand Regent Thragg established himself as the main villain of the comic series over halfway into its run, and when he asserted his dominance in the bloodiest way possible. In fact, his most violent fights stand out as the most brutal moments from one of the most violent comic series of all time.
Thragg vs. Everyone
By Invincible #75 the comic had already established some of its heaviest hitters. The title character alone could topple buildings, and full-blooded Viltrumites alongside him like Thaddeus and Omni-Man were shown to be even more powerful. Battle Beast was one of the most fearsome foes Invincible ever faced, and yet in #75 all of those characters (and Invincible's little brother Oliver) were completely obliterated in the debut of Grand Regent Thragg.
Born and trained to be Viltrum's greatest warrior, Thragg quickly demolished his way through the series strongest characters to claim the top spot for himself. He crushed Oliver's arm in his hand and literally punched the boy apart, ripped Thaddeus' head straight from his body, knocked Battle Beast out of the fight with one blow, and overpowered Omni-Man and Invincible both at the same time. Despite Omni-Man being one of the strongest characters in the series, Thragg runs his arm through the hero's chest and nearly kill him. It was a brutal and effective display of power, and Thragg was only getting started.
Thragg vs. Battle Beast
Battle Beast is a beautifully simple character, with almost everything you need to know about him present in his name. He is a beast who craves battle, hungry for a worthy opponent who can stand up to his might and grant him a warrior's death. For so long he conquered every foe thrown at him, winning wars for his people, before venturing out to find his worthy match. It was only when Thragg punched him away so casually in their first fight that he knew he had finally found his match.
Battle Beast and Thragg's rematch is one of the most epic fights in comic history. Despite both characters starting the fight disemboweled their battle rages on for days, spanning the globe of an alien planet so rapidly they are impossible to track as they demolish every city left in their wake. In the end, Thragg proves victorious, claiming Battle Beast's hide as a new royal mantle to mark their battle, and it's probably the only time Thragg came so close to losing a fair fight.
Thragg vs. Dinosaurus
When it comes to unfair fights, there were few mismatches greater in the pages of Invincible than the duel between Dinosaurus and Thragg. While Dinosaurus proved earlier to be strong enough to go toe-to-toe with Invincible himself, Thragg stood several tiers higher than Invincible and barely had to prove it when the two faced off. Overlooking Invincible's ailing form Thragg nearly killed the hero, and in seeking to save his new friend's life Dinosaurus lashed out at the Grand Regent. And barely survived.
Dinosaurus's fangs shattered around Thragg's head. When he slashed at Thragg's chest, his claws broke off and left his hands bleeding. For his trouble, Thragg smashed Dinosasurus through the moon base and cracked his jaw open. In the end, the dinosaur only managed to save himself through his wits, having previously planted bombs in the base that forced Thragg away so that he could make his getaway with Invincible's body, and his own, barely intact.
Thragg vs. Oliver and Invincible
One of the best things about Thragg's intense early fights is that all of his subsequent clashes were infused with a sense of greater tension. That only made the scene where Thragg finds Invincible, Atom Eve and their daughter alone on an alien planet all the more fraught. Though Invincible's brother Oliver attempted to side with Thragg previously, he had a change of heart at the last minute, and what ensued was a battle against some of Invincible's dearest loved ones that carried some of the biggest emotional hits in the series.
While Thragg's own daughter battled Atom Eve, Oliver and Invincible tried desperately to keep Invincible away from the hero's young child. Yet again, Thragg pulled off his signature move of running his arm straight through his opponent's chest, ending Oliver's life once and for all. Enraged by his brother's death, Invincible tried to fight back, but Thragg literally tore him in half down the length of his torso. It was only the last-minute intervention of Atom Eve that saved the hero's life, rebuilding him to be even stronger for a rematch against Thragg. And he would need every bit of strength he could get.
Thragg vs. The Sun
The final showdown with Thragg takes up almost an entire issue all to itself, and with a battle of such epic proportions, it's easy to understand why. Considering that the fight starts with Thragg throwing his own children at Invincible so hard that they explode apart against the hero's costume, it's taken as a given that the fight would be one of the comic's most brutal. As the two square off in the heart of the Sun itself, the battle only grows more violent.
Robot's intervention aids Invincible by temporarily providing him some armor from the Sun's heat, but he and Thragg duke it out amidst the fiery plasma as their costumes, communication devices, and layers of skin steadily burn off. In the end, they are not able to even hear one another, but Invincible reflects on the strength his loved ones give him as he wins the fight once and for all. Allen the Alien's intervention save's Invincible from burning up, but Thragg's body cremates in the sun to perfectly punctuate a violent life with a violent end.