Countless civilisations die in the blink of an eye every time Galactus devours a world. He can only sustain himself by consuming entire planets. Galactus's villainy and evil nature make him the strongest comic supervillain.
Anti-Monitor's power comes from the energy he absorbs. The supervillain has the most blood in his hands as he derives energy from worlds causing severe devastation. He seeks the corruption and destruction of the multiverse.
Mephisto in Marvel comics is demonic, immortal, and the hellish representation of the underworld. He clashes with several heroes like Doctor Strange and Wanda. Mephisto can see across time, manipulate the universe, and alter minds.
Trigon is Marvel's closest counterpart to Mephisto. However, his history drenches in more blood. He is extra-dimensional and ruthless, as he can bend space, time and reality.
Darkseid 'Prince Uxas' was murderous and selfish. He constantly sought power and killed his brother to obtain the Omega Force. He was in frequent conflicts with the Justice League.
Urizen's description itself can give someone goosebumps. He is a dark entity whose status rises above Heaven and Hell. There's no killing Urizen, only prisoning him away for another inevitable rampage.
The four phases of the Marvel Universe might have seen Hela or Thanos. But, both of them have no power compared to Lady Death. She is the grim reaper of every living being across the Marvel Universe. Deadpool's infatuation with Lady Death symbolises his desire to be released from his current state of self-healing and die.
One of Superman's most formidable foes is Brainiac. His level of intelligence exceeds the human brain by seven centuries of advanced knowledge and analytical capabilities.
The Mad Titan, Thanos wanted to eliminate half of life in the known universe. Comic fans have already seen him in the Marvel Cinematic Universe. It took an entire army of superheroes to halt his evil plans.