Medama Oyaji, often referred to as 'Eyeball Father,' is a fictional character from the anime and manga series GeGeGe no Kitaro. He is the father of the main protagonist, Kitaro, and is characterized by his unique appearance, consisting of a single giant eyeball. Despite his small size, Medama Oyaji is wise and knowledgeable, often providing guidance and advice to Kitaro and his friends. He plays a significant role in the series, acting as a mentor and a source of wisdom in their battles against various yokai and supernatural forces.