Zim is a centaur who runs the Armory. He also goes by "Big Z." His original name may be Zimarianelos (he claims he answers to it in really bad fics).
Zim is described as "big, strong, [and] no-nonsense," and has a deep bass voice. He encountered Agent Techno-Dann during the latter's first minutes in Headquarters, and helped him find his feet and some quality armaments.