Venom

He is Diablo's direct subordinate and a Black Colored Demon, belonging to the Black Numbers, however unlike Testarossa, Ultima and Carrera he doesn't dare to question his superior's orders. It is said that he is very young but was born with a Unique Skill, making him a Unique Demon. Venom has one hundred subordinates at his disposal and when he encountered Diablo in Hell his stubborn disposition in the face of continuous beatings made the Black Primordial think he might be useful to Rimuru.

He is also a reincarnator like Rimuru.

Trivia
Venom is named after the Hennessey Venom supercar. This follows the pattern of many of the Demons being named after cars in this anime.