Krassus was an Orion slaver in the 24th century. In 2372, he intended to sell an Orion slave girl named Zina to Barsamis, but took a liking to her and decided to keep her for himself. When Barsamis protested, Krassus killed him with a knife.
In 2373, Krassus gave Zina to Mackenzie Calhoun to satisfy a gambling debt. He later tried to ambush Calhoun with his knife, but Calhoun shot him with his blaster, critically injuring him, then used his knife to slash his throat, killing him. (TNG novel: House of Cards)