Magistrate

"How can you kill friendship, Magistrate?"

"Quite simply, Zgorian. By slaying those who would be friends".

The Magistrate is an alien dictator and an enemy of the Hulk, he is one of the darkest villains in the fact that he never got punished for his horrific crimes and actually succeeded in all his plans : to the point Hulk could not even lay a finger on him (it is extremely rare in superhero fiction for a hero to fail in not only saving someone but for the villain to outright win (and stay victorious).

The Magistrate was a leading figure within the alien species whom Zgorian belonged, while Zgorian was a pacifist and deeply cared for all life the Magstrate was a malevolent being that saw peace and compassion as crimes, indeed it was revealed that he had banished Zgorian from his society simply for being a pacifist.

After Zgorian befriended Hulk the Magistrate arrived alongside several soldiers and attacked, Hulk was powerless as the Magistrate declared he had finally come up with a suitable punishment for Zgorian's crime (which was showing mercy to an enemy at some point in the past): Zgorian was unfailing in his compassion and did not fight as the Magistrate ordered his execution.

Hulk was furious and desperately tried to save his friend but was beaten mercilessly, after Hulk was subdued the Magistrate's soldiers opened fire on Zgorian and the dictator left - completely free to continue his rule and was never heard of again. What followed was one of the most tragic moments in Hulk's many adventures as the raging giant crawled over to the corpse of his slain friend and gently placed a loving hand on him before he was teleported away from the dimension, still grieving the loss of one of the few beings that genuinely treated Hulk kindly.