I can't believe how long I've gone without appreciating M. C. Escher. When I was a kid my elementary school had a mini-exhibit of his tessellations pictures, but I mostly knew him for his stairs pictures. And stairs pictures for Escher like the melting watches for Dali: so overused in conjunction with his name that I figured it was all he had to offer. Fortunately, I saw my first Dali exhibit around puberty and had that view corrected, but I've never been to an Escher exhibit.
However I've recently rediscovered my childhood obsession with polyhedra, and in the process stumbled across some of the work he's done that incorporates them, and it's amazing.
"Stars"
"Double Planetoid"
"Gravitation"
"Snakes"
He also did sculpture, as with "Icosaëder"
And check out "Mosaic I" and "Mosaic II":
Holy fuck! Escher certainly rivals Dali—and may even have replaced him—as my favorite artist!