Hydro Contaminators

The Hydro Contaminators appeared in 1996 TV series called Power Rangers Zeo. The Hydro Contaminators were a group of aliens that have water pollution-motives. The Hydro Contaminators attacked Aquitar by dumping poison into its waters. One came to Earth by following Cestro and planned to contaminate Earth's water supply. That Hydro Contaminator was destroyed by the Zeo Blaster.

The Aquitians and the Hydro Contaminators later settled their differences.

Another Hydro Contaminator was seen to receive the Neo-Plutonium Armor but he was not used for battle. It's possible it's the same one that followed Cestro.