Cestro

Cestro, played by Karim Prince, is the Blue Aquitian Ranger. He is entrusted with the power of the Blue Battle Borg.

Like his Mighty Morphin counterpart, Billy Cranston, Cestro is a technological genius. When Billy successfully managed to restore his own age by means of the Power Coins before they were destroyed, he and Cestro frequently worked together to find a similar cure for the other Rangers - as well as finding a means to keep the Aquitians hydrated with pure water. In this way, Cestro was the Alien Ranger who received most attention in storylines (alongside Delphine, the team leader).

Cestro had a guest appearance in Power Rangers: Zeo, in which he came to Earth again, seeking Billy's help to fight off a menace on Aquitar called the hydro-contaminators. Billy's trip to Aquitar saw the beginning of the story arc in which he was permanently written out of the show. Indeed, the Aquitian that Billy falls in love with on Aquitar, Cestria, is believed by some to be Cestro's sister or similar relative (though others dispute this because of the different races of the actors playing the two characters).