Belial Kaiser, known as ベリアルカイザー in Japanese, is a formidable antagonist in the Ultraman Zero series. As a fusion of Ultraman Belial and the powerful Kaiser Belial armor, he is driven by a deep desire for revenge against Ultraman Zero and the Land of Light. His cunning intellect and immense power make him a significant threat to the Ultra Warriors. Throughout the series, Belial Kaiser seeks to conquer universes, standing as one of Zero’s most dangerous and persistent foes.