Gelmud prided himself as a high-class Majin. He was the type of person who would hide his true intentions behinds the language of a polite gentleman.
For 300 years, he had been planning a species war. However, Veldora's disappearance caused his plans to spiral out of control, so he gave up on inciting a war between the named monsters born from the goblins, lizardmen, and other such races. Instead, he sent out the Orc Lord. The Orc Lord decapitated and ate him.
He is clearly above an A-rank.
He has a regeneration skill.
Shisha no Koushin'enbu (Death March Dance).
Orc Lord: The Orc Lord was loyal to his order; he planned to make him the new Demon Lord and manipulate him from behind the scenes.
Rimuru Tempest: When Gelmud first heard of Rimuru and saw him, he hated him for ruining his plans in creating a new Demon Lord.
Benimaru: Gelmud was affronted when he approached the Ogres' village and Benimaru rejected his offer of a name.