Although he gained fame with his gritty Blueberry Western serial, it was his surreal comics that I came across in Heavy Metal magazine (which I believe he co-founded) that grabbed my attention. His work seemed to combine two contradictory features -- a simple and obvious (at times bare) line-drawing style with an amazing attention to rich detail.
When drawing established comics characters like the Silver Surfer, Galactus, Spider-man, the Fantastic Four's Thing, or Iron Man, he managed to make them distinctly his own. Behold this incredible portrait of Batman sitting on a ledge, his cape draped along the side of a Gotham building.
Some of the films for which he provided conceptual designs include Alien, Tron, Willow, and The Fifth Element. That latter project ended up in a lawsuit against director Luc Besson, and unfortunately I'm not familiar with all the details, but I believe he lost the suit. For all its flaws, one of the most appealing aspects of The Fifth Element was the undeniable inspiration that came from the artwork of Moebius, especially in those futuristic cityscape scenes.
Moebius was 73 years old, truly a one-of-a-kind. May he rest in peace.