Herbert Landon

Herbert Landon was the main antagonist of The Mutant Agenda - a crossover between the 90s Spiderman cartoon and the X-Men, he was a brilliant but completely immoral scientists who specialized in mutant DNA and was at some point a friend of Beast prior to his transformation into a mutant.

Unlike Beast Landon would continue to harbor a deep hatred of mutants his whole life, to the point he created a chemical substance specifically for the purpose of killing all mutants - so great was his hatred that he openly stated he would wipe out all mutants using his invention, which Beast rightfully warned was basically genocide.