Only one of these exists in the world. And that, my friends, is a tragedy.
LEGO builder Zane Houston put this beast together for a contest, providing some back-story as to why Bowser has given up on air power and turned to bipedal mechanised killing machines:
Years of battling Mario and Luigi has taken its toll on Bowser; to compensate he constructed this giant mechanical version of himself to do his bidding. Equipped with razor-sharp claws, spikes, and a flamethrower powerful enough to scorch that mustachio right off your face. Stay in your pipe, puny plumber!
"Stay in your pipe, puny plumber"? God, he's even got a perfect catchphrase. You're getting tens from all the judges, Zane. All of them. Even the East Germans.
Mecha Bowser [Flickr, via Brothers Brick]