Mondo the Magician was a fictional character in a book titled Grumble the Magic Elf (or possibly, since Rita knew him, a powerful sorcerer trapped in a children's book, cursing it as a result). Mondo had put a spell on Grumble the Elf, turning him into a grouch. Rita Repulsa was an old friend of Mondo. When Kimberly, Rocky, and Tommy were trapped in the book & turned to Mondo for help, he turned them away. After the three Rangers were eventually able to escape, Rita was able to free Mondo from the book, allowing him to attack the city. He was returned to the book after being struck twice by the Thunder Megazord's Thunder Saber.
He is the first Power Ranger monster, who's Sentai counterpart is a major villain.