Hydrax

Hydrax was a Deltraxian and a member of Darkarayus' army. Serving directly under Serpentinx, Hydrax was considered to be the 'muscle' of the group, always angry and wanting to cause destruction in the name of Darkarayus. He quickly came into contact with new member Broodwing, who was only in it for the profit. Driven to madness by their inability to defeat the rangers, Hydrax bought his own vial of Elixir from Broodwing, enacting an elaborate plan to dispose of the rangers once and for all. He grew giant and fought them in their Megazord, but was ultimately defeated, being heavily wounded. Crawling on the ground as he bled to death, Hydrax was taken in by Serpentinx against his will, being injected with a serum that temporarily elongated his life while Serpentinx upgraded him with robotic limbs, rebuilding Hydrax as the horrific Cyber-Hydrax.

He later assisted Serpentinx in an assassination attempt on Darkarayus, but the two failed and Serpentinx was sentenced to die. Serpentinx was saved in the end by Cyber-Hydrax, and together the two started their own evil faction, plotting to destroy both the rangers AND Darkarayus.

However, in the end, Cyber-Hydrax betrayed Serpentinx, killing him, before revealing the truth to everyone-in reality, he was Zentar, the leader of the Council of Peace who was thought to have been killed by Darkarayus. Zentar, who became obsessed with greed, manipulated Darkarayus to run off and start an evil army before faking his own death at Darkarayus' hand. Disguising himself as Hydrax, a member of his army, Zentar made profit off of the war by selling Darkarayus weapons under a new alias. His flow of cash was interrupted when they were all sealed away at the end of the war and was again threatened when Broodwing came into the picture, hence why he and Hydrax never got along.

He then revealed his new plan to enslave all of humanity in order to force them to make weapons and equipment, which he would then sell to the highest bidders in order to become the richest being in the galaxy. Killing Galactamus and Darkarayus, he took over the latter's army, as well as the small remnants of Serpentinx's army, and began to work on his master plan of taking over Earth.

However, he was defeated by the Galactic Force, who destroyed him once and for all, saving the Earth and the entire galaxy in the process.