Also known as: イム(ONEPIECE), ネロナ・イム聖
The main villain of the manga and anime One Piece.
Heavy spoilers for episode 885/chapter 906 and later follow here:
Saint Nerona Imu is the secret occupant of the "Empty Throne (One Piece)", making him the highest-ranking member of the World Government above even the Five Elders (a.k.a. Gorosei). As a result, he is the overarching antagonist of the whole series.
Before his face reveal, he appeared as a Silhouetted Hooded figure with distinctive ringed Red Eyes and a very tall Crown. That design is now tagged under Nerona Imu (Silhouette).
He was shown to have a dark skin, White Hair and Demon Horns. Imu is the user of the Devil Fruit "The Devil's Fruit", which grants a transformation into a devil, immortality, the use of the abyss magic circle and the ability to bestow these abilities on others (and also to take them away at any time).