Zachariah Grizlock: [USA] Supreme's arch enemy from Rob Liefeld's part of the original Image Universe.
Zagreus: [Greece] Dionysos, the Greek god of wine, agriculture, and fertility of nature, and the patron god of the Greek stage.
Zaxton Regulus: [USA] Doctor Regulus, the pre-crisis version of the LSH villain (DC Comics).
Zeke Midas Wolf: [USA] Disney's version of the Big Bad Wolf from the European Folk Tales.
Zeus: [Greece] Supreme leader of the World above from Greek Mythology.
Zilly: [USA] Hanna & Barbera's mechanic and pilot.
Zoofus: [Danmark] Dyrepasseren fra Torben Osteds serie Fodring Forbudt.
Zoyvod: [USA] Villain from Dale Keown's part of the original Image Universe/Full Bleed.
Zzzax: [USA] Electrical monster from Marvel Universe (616 continuity).