Mesogog

"Why must you continue to fail?"

- Mesogog to Elsa and Zeltrax after a failed mission to destroy the Rangers.

Mesogog is a dinosaur-human hybrid and the main villain of Power Rangers: Dino Thunder.

History
Mesogog was created from a ground-breaking experiment Dr. Anton Mercer had been performing with dinosaur DNA. However this accidentally transformed him into the monstrous megalomaniac, Mesogog, who sought to send Earth back into the age of dinosaurs with all humans transformed into reptilian hybrids like himself. They continued from then on to shift between Mercer and Mesogog in a Jekyll and Hyde relationship with each aware of the other, but having two distinct personalities.

The dinosaur hybrid recruited Elsa and a cyborg warrior called Zeltrax, whom he created from the remains of Terrence "Smitty" Smith, a former associate of Tommy Oliver's, to aid him in his attempts to conquer the world. Mesogog also utilized an army of creatures called Tyrannodrones, dinosaur based humanoids that Mercer and Tommy had created. He then set up his lab/base, which was full of genetic samples he could use to create monsters, and was ready to put his plans in action. But Mesogog plans were interrupted when Tommy managed to steal the three Dino Gems and use them to create the Dino Thunder Power Rangers.

Mesogog began sending his monsters against them, only to be bested again and again. However things began to sway in the dinosaur hybrid's favor when Mercer's son, Trent, found his lab and the White Dino Gem that Mesogog had in his possession. It transformed him into the White Dino Ranger, who fought against the rangers but was not loyal to Mesogog until Trent found out that he was also Mercer. The White Ranger joined his side, but Zeltrax convinced the dinosaur hybrid that Trent was a traitor so Mesogog hooked him up to a machine that would drain his life energy. However Mercer regained control of their body and freed Trent before it could take all his life energy and told him to fight alongside the other Power Rangers.

Later, Mesogog joined forces with the returned Lothor, who had turned the Wind Ninja Power Rangers evil. But he regarded Lothor as an idiot and did not trust him completely, planning to get rid of him as soon as the other rangers were destroyed. But the Dino Thunder Rangers, the Thunder Ninja Rangers, and the Green Samurai Ranger turned the Wind Ninja Rangers good again and defeated Lothor and Mesogog's forces. Mesogog and Lothor fought with the dinosaur hybrid emerging the victor, shrinking the evil ninja lord and putting him in one of the jars where he kept genetic samples for monsters. Some time after this, the dinosaur hybrid succeeded in using a formula that separated him from Mercer, increasing his mental instability and determination to see his plans succeed.

Mesogog rid himself of Elsa, needing her energy to power a cannon he was using in his plans, but the rangers used a bit of trickery with the Dino Gems to destroy the cannon and Mesogog's base. However the dinosaur hybrid was able to survive and reappeared after the rangers' defeated Zeltrax, using energy he'd absorbed from the gems to mutate into the Mesomonster. He took on the Rangers, proving nearly invincible and even split into four copies of himself, but the Rangers used all the energy in the Dino Gems to destroy the Mesomonster.

Powers
Mesogog has proven that he is quite skilled in hand-to-hand combat and possesses psionic powers that he can use as a means of torturing his enemies or his allies if they fail. He is quite intelligent in terms of genetic technology, having created a device called the Geno Randomizer that can take samples of animal, plant, and machine to create monsters. Mesogog can also sense Dino-Gems and as the Mesomonster, he is even more powerful, proving practically invincible and can split into copies of himself.

Trivia

 * When Mesogog was about to launch his first attack on Reefside, the city where Dino Thunder takes place, he said that the people would probably attribute it to a returned Lothor.
 * Some fans would compare him to Pinhead from the Hellraiser franchise. Both of their choices of garb hide most of the anatomy with long black leather (with the exception of the hands and head). Their personalitys both show a cold, no-nonsese demeanor and, when they seperate from their humanity, become more sadistic and unruly.
 * Mesogog is an example of a main villain in Power Rangers who has no direct counterpart in Super Sentai, being entirely American-made.