Rotox (voiced by Mark Wright) is the first mechanical opponent faced by the Mega Rangers and the primary antagonist of the episode "The Human Factor". He is a prototype who is sent out to analyze the Rangers' strengths and weaknesses, for Vrak intends to defeat humanity through the Robots without making the same mistakes as the Insectoids and Toxic Mutants before them. In the season finale episode of Power Rangers Megaforce "End Game" three robotic clones of Rotox, the Water Rotox Army, serves as the final monsters for that season.
As Admiral Malkor enters his cocoon, Metal Alice is completed by Vrak and creates her first experimental machine, Rotox. To demonstrate the might of machines, she attacks him but loses her left leg. After pulling herself together and having earned Vrak's approval, she sends Rotox to attack the city, drawing the attention of the Megaforce.
The Rangers try to fight him but are outmatched and restrained by Rotox's strength and weaponry. Robo Knight later arrives but is caught by surprise and temporarily incapacitated. The Rangers then break free from the chains restricting them and ascend into the Ultra Mode, which proves more than enough to defeat Rotox.
However, Metal Alice wastes no time and collects his remains, repairing and upgrading him as Rotox DX. Claiming to be ten times stronger than before, he makes short work of the Rangers, going as far as catching and dissipating the Megaforce Blaster's Dynamic Victory Charge with a mere sequence of arm twists.
In a later confrontation, Rotox teams up with Metal Alice in battle and they outclass the Ultra Mode. It takes the full power of the Megaforce to finally defeat Rotox DX. He is enlarged by the Zombats and fights the Gosei Grand Megazord and the Gosei Ultimate Megazord. After being disarmed of the weaponry on his hands by Gosei Grand, Rotox DX is defeated by Gosei Ultimate's Ultimate Strike.
Three robotic clones of Rotox are later used during the final onslaught led by Vrak, Metal Alice and The Messenger in the season finale episode of Megaforce: End Game. This model is called the Water Rotox Army. Nevertheless, they are far less powerful and resilient than Rotox or Rotox DX and are easily defeated, each taken down with a twin strike from the Rangers' regular weaponry.
As the first of a line created to demonstrate the superior strength and endurance of robots, Rotox is tough and confident in his abilities. He follows his assignments to the letter and has a taste for extreme destruction. Also, he is very enthusiastic when it comes to fighting, with his catchphrase being "Ready for Action!".