Roswaal L Mathers is the lord of the Roswaal Mansion and the descendant of the original Roswaal. It is later revealed that he is in fact the original Roswaal, who has been possessing his descendant's bodies. Roswaal has long indigo hair with heterochromic eyes, the right one being blue and the left one being yellow. His eyelids are decorated by purple eye shadow, though the left eye's is longer.
He wears a lavender coloured make-up which accompanies his unusual outfit comparable to those similar to a clown or jester, consisting of a black hat, a top and bottom with different shades of purple, along with red and black boots and a cape.According to Echidna, the original Roswaal had long, dark gray hair and yellow eyes. Roswaal cares about Ram and Rem, becoming concerned when Rem died of an unknown cause. Because of his relations with Demi Humans, he has been rumored to have a thing for them.
However Garfiel speculates this is actually because he's been gathering halfs to the Sanctuary. In actuality, his body is possessed by his ancestor, whose purpose is to meet his teacher Echidna again at any cost, even if that meant sacrificing himself or those close to him, making Echidna describe him as being "a little too earnest". He has figured out that Subaru is looping through some method, causing him to challenge him, and subsequently lost. Though he has agreed to help him after losing, he has threatened to force him to loop if he makes a mistake. Mage: Roswaal is a mage capable of using magic of all six elements. Despite being the original Roswaal, he is mentioned to be much stronger than before Divine Protection (加護 Kago): Roswaal has the Divine Protection of Sorcery, which makes him compatible with all six magic elements, enabling him to use the magic perfectly. Using this Divine Protection, Roswaal is considered to be the best in the kingdom in terms of mana usage, power, and speed, and is recognized to be as strong as one army. Melee Fighter: Roswaal is able to fight physically, using moves such as throwing techniques against opponents.