Alright I don't look at Van Gogh's or Picasso's, or I guess I could say I do but I really cannot say I critique because in a sense they are above or beyond me, and generally just not something I really like. I love Mark Ryden and I think he is awesome, here is one of my favorite pictures by him.
*sigh* This is a hard one... I almost hate making a list because I feel bad if I forget someone. The latter four on here are mainly here because they've been an influence on a lot of my own art.
Alphonse Mucha Henri de Toulouse-Lautrec William Adolphe Bouguereau Caravaggio Norman Rockwell Jamie Hewlett Charlie Bowater Tracy Butler (I normally don't care for anthro stuff, but her comic, Lackadaisy, is just...damn.)
I really enjoy the works of both Dali and Van Gogh along with many others.
Currently I am obessed with the works of Audrey Kawasaki www.audrey-kawasaki.com/ I have been inspired by her works in my own field of apparel design. In fact, I am currently creating a dress inspired by one of my favorite paintings by her for a Elsa Schiaparelli inspired student exhibition. For those of you who do not know who Elsa Schiaparelli was, she was a fashion designer during from the late 20s till the 50s. Her designs were greatly inspired by surrealism. She and Dali even collaborated on a few of her garments. en.wikipedia.org/wiki/Elsa_Schiaparelli
I know many people put older artists on here (Gogh, Picasso, Dali...) and I love those guys (and many other "older" artists) but my favorite artist has to be Bill Watterson, creator of Calvin & Hobbes.
Discovered his stuff when I was a little kid in elementary school and I've re-read everything he's done through out my life. It was one of those books that I could read and it would make me laugh and just feel good, even when there was stuff going on. When I finally had enough money, one of the first things I ever bought was his entire collection of work.
I know it's more "newspaper comic" style but I consider Bill to be among the greatest of artists there have ever been.