Mefilas Seijin, known as Alien Mefilas, is a recurring antagonist in the Ultraman series. He is a highly intelligent alien who often challenges Ultraman not just with brute force, but with cunning and psychological tactics. Mefilas Seijin is known for his calm demeanor and persuasive nature, often attempting to manipulate humanity rather than conquer it outright. His unique approach and intellect make him a memorable and formidable foe, playing a significant role in the Ultraman universe.