Me neither til I finally picked up a book on Giger and there's the Windowlicker staring at me from the first page I flicked to. I always bought into a rumour (possibly just amongst my friends) that it was a munge of Aphex Twin's face and Chris Cunningham's face.

It was this piece that first gave me that odd moment we're seeing a lot of in this thread as I had always assumed Giger was a contemporary of Escher or even earlier. Seeing Windowlicker was dated 1999 really gave me a surprise.