Derek is a Dry Bones and one of the main antagonists of Shy Guy's Land
Derek used to be the owner of Crasher Casino in Northern France, which he took half a dozen years learning French to speak to the customers, unlike most of the other villains Derek was a more innocent character before snapping to his evil self, where he took a life of greed and making slaves of innocent. Where he used his Casino as a "Base" for him and his goons, as well as his sidekick "Booster Strange". In 2013 he made it where for people to do a "chance at luck" type of game where people who fail are forced to work as his slave even after death where they'll be resurrected to skeleton ghosts.
Derek is one of two characters that isn't a humanized version of the Mario monster he is based off of, as in my AU, koopas, yoshis, and the main characters stay the same. So Derek keeps his Dry Bones, Undead Koopa look, he wears a purple suit with a red brooch, and he wears blue boots with yellow soles, and wears a dark blue top hat.
Derek is shown a stereotypical, greedy, snobbish, tightwad, but he is shown much more sadist as he enslaves innocent bystanders and them even being slaves after death, to explain it all... he is like a sadistic Scrooge Mcduck.
Derek is encountered in chapter 3-6, where Lionel encounters him at the Casino where his comrade Booster Strange takes Lionel to the game room for Lionel to possibly be forced to be Derek's slave. Lionel enters the Game Room where the doors block off with iron gates, and Lionel's forced to do his chance at escaping, or becoming Derek's new Shy Guy slave, however Lionel fails. But Lionel didn't want to back down, he wanted if he had to... defeat Derek if he had to so he could escape, however Derek is immortal in a way being he can reconstruct himself after being knocked down, but Derek grabs Lionel and says he instead feels like he has one too many slaves, so he decides to kill Lionel with the ol' pot of acid, however one of Lionel's friends Alonzo the Bullet Bill saves Lionel where he knocks Derek out and unties Lionel to escape, when Derek tried to stop Alonzo from getting away, Alonzo shoves Derek into the pot of acid which Derek officialy dies being dissolved in the acid.