Moebius (aka Jean Giraud) is one of my all time favorite comic artists. He helped define the French comics scene in the late 1970s with his work in Metal Hurlant (precursor to Heavy Metal). If you aren't very familiar with Moebius I'd highly recommend starting with The Incal, a science fiction serial written by Alejandro Jodorswky (writer/director of El Topo and Holy Mountain). The Incal was originally serialized in Heavy Metal, but was later reprinted as a series of three graphic novels by Epic and, although out of print, is readily available in these editions.
An amazing and beautiful video tour of Moebius art (DOUBLE-CLICK TO OPEN IN A NEW WINDOW):
It's wonderful to watch Moebius in action. Here are some video clips of him drawing: