MZ are a motorcycle manufacturer based in the former East Germany. They are one of the oldest manufacturers of motorcycles in the world, having been established in one form or another since 1908.
MZ has been through many phases. They started off as DKW, became part of the mighty communist IFA, were bankrupt a couple of times, set themselves up as MuZ for a while, and are finally back to MZ.
The most striking thing about MZ is the sheer number of innovations they introduced into motorcycling. They essentially reinvented the two-stroke engine, under the direction of Walter Kaaden, one of the Peenemunde V2 designers. They invented the rotary disc valve and the dual-cone tuned expansion chamber exhaust. They designed the BSA Bantam, possibly one of the most famous motorcycles of all time.
Possibly what MZ are most famous for is the series of regrettably functional two-stroke motorcycles produced during the communist era. Starved of resources, they produced possibly the most durable motorcycles of all time, the TS series. Many thirty-year-old TS250s are still running today. In the 1960s, MZ's revolutionary advances in hydrodynamics led them to win every competition they entered, until one of their engineers defected and gave the secrets to Suzuki. Suzuki haven't looked back since.
Nowadays MZ produce a number of interesting four stroke models, all with a unique Saxon twist. Personally, I'd really like an RT125.