Also known as the Wizard Marshall, Zelretch of the Jewel, and the Kaleidoscope.
One of the five True Magicians. Symbolized by gemstones, he's best known as an eccentric old man who despised evil with genuine passion but found self-righteous do-gooders equally ridiculous. He took on plenty of pupils over the years, though none ever established a successor lineage worthy of his legacy.
His reputation speaks for itself—he once fought the King of Vampires in single combat and stopped a falling boulder from the heavens through sheer magical force. That's the kind of monster he was. Problem is, age has caught up with him. Whatever made him untouchable in his prime has faded, and his magical output just isn't what it used to be.
Fate/Stay Night: Heaven's Feel
Zelretch shows up at the Clock Tower to meet Rin Tohsaka after she successfully recreates his Jeweled Sword with Shirou's help. He's genuinely impressed—impressed enough to take her on as a protege and get all her legal troubles erased. He'd written off the Tohsaka line as unremarkable (especially given where they started), but six generations in, they've actually proven themselves. In the True End, he leverages his Clock Tower connections to get Rin fully acquitted for her involvement with the Greater Grail's gate.
He pops up briefly in Carnival Phantasm.
Fate/Kaleid Liner Prisma Illya
Zelretch created Magical Ruby and Magical Sapphire and handed them off to Rin and Luvia to hunt down the Class Cards. He appears in brief scenes with Waver Velvet/Lord El Melloi II.
Fate/Strange Fake
Content compiled by AnimeList.moe from publicly available sources.