Supreme's alrer ego from Alan Moore's run was an artist too I believe.
I think this has been done here before, someone provided a link with dozens of characters who were comic book artists, but included in the list were TV characters, and characters in films. I joined in September 2011, so it was between then and now, but closer toward September than March. I forgot what subforum it was in, but maybe that thread can be found and linked here.
This is still a good topic, but I think you should include fictional comic book artists from TV shows and movies, such as Ted Knight in "Too Close For Comfort" and Lea Thompson's character on that TV show about a newspaper strip artist. Then there was that movie with Bruce Willis, I haven't seen it but I heard there is a comic book artist he consults with to figure out why he is gaining superstrength. I think that flick was called "Unbreakable."