Warthog driver from TM2 is not a zombie, the guy isn't even dead. TM3 you could argue his character portrait looked like a zombie but even then he wasn't. TM2 he was old and after winning he asked to have a younger body. In result he got the younger body but the head stayed old.
This is one of my favourite games of all time. Here is my list: S- Axel, Shadow A- Warthog, Thumper, SweetTooth, Mr Slam B- Mr Grimm, Spectre, Outlaw 2 C- Roadkill, Grasshopper Shit- Hammerhead, Twister