Miraculous Hamburger
Also guys being biologically immortal is a thing, a vampire could just be that. The most basic explanation could be that all of his cells have been optimized into controlled cancer cells, so they can replicate unlimitedly without any problem. So maybe not undead, but biologically immortal. Cause our alleles get shorter when we replicate, but not for cancer. There are a ton of other things that can kill him, like disease, hunger, but they dont fall under biologically immortal,