While I can't really remember how I found this place, I've taken quite an interest to it thanks to videogame tropes such as That One Boss.
My first contributions to the beat-em-up page of that trope is R. Bear from Streets Of Rage and Slice and Slisaurs from the Cadillacs And Dinosaurs arcade game, but I will be on the lookout for more obscure examples of such, even those of other genres.