Saint Roswald (Rosward Sei)
Roswald is a World Noble with the privilege of living in the Holy Land of Mariejois. Among his family members, he's generally portrayed as the most levelheaded—at least when it comes to discipline, occasionally scolding his children for stepping out of line.
His first major appearance shows him with his daughter Shalulia watching over one of his slaves, Dias, a former pirate captain of the Acumate Pirates. The scene is pretty brutal: after Roswald's dog urinates on the man, Shalulia casually shoots him without blinking. There's a demon-like figure lurking in the background during this scene, which is later revealed to be pirate captain Jean Bart.
Roswald turns up again at the Human Auctioning House alongside his son Charloss and daughter Shalulia. He gets genuinely annoyed with Charloss for bidding on Camie, showing he does have some standards, even if they're twisted by his World Noble upbringing.
He's known among fans for maintaining what amounts to a "Pirate Captain collection"—basically a roster of captured pirates he keeps as slaves, which is pretty on-brand for the morally bankrupt nature of the World Nobles.
Content compiled by AnimeList.moe from publicly available sources.