Magus

Magus (Maoh in the Japanese version), also known as "The Fiendlord", is a dark wizard who waged war against the kingdom of Guardia with his army of "Fiends".

Origin
Magus was originally named Janus and was the prince of a magic kingdom in the sky, called Zeal. Zeal was divided into four islands in the sky which overlooked the Earth. The people of Earth were seen as primitive and looked down upon by the Zeal people because they didn't know magic. Janus and his older sister Schala were the children of the evil Queen Zeal, who wanted to awaken Lavos and make herself immortal. Janus was anti social and bitter growing up, he trusted no one except his cat Alfador and Schala.

When Crono and friends visit the city of Enhasa on Zeal, Janus tells them "the bitter black winds howl, one amongst you will perish" and then he disappears.

When Crono confronted Lavos at Queen Zeal's Ocean Palace, he was killed and the power of Lavos caused the kingdom of Zeal to collapse and fall down to Earth, destroying it. Some citizens of Zeal survived and lived with the primitive people of Earth, deciding to start civilization over from the beginning. The power of Lavos also caused portals to open and suck the three gurus, Melchior, Gaspar, and Belthasar away into different time periods. Melchior became a blacksmith in the Middle Ages, Belthasar was trapped in the distant future, and Gaspar was trapped in the end of time where he would meet Crono and help him on his journey to defeat Lavos. The young prince Janus was trapped in the Middle Ages in Truce Canyon.

Middle Ages
Janus was found by Ozzie and three blue imps who would have killed him if he had not defended himself with his magic. Janus became feared by Ozzie and became a ruler amongst monsters, he promised to give them their own kingdom, a paradise for monsters. Janus grew up, feared by monsters and humans, and was called "Lord Magus" or the Fiendlord.