I think the "my faves" concept is a bit silly for a cell phone plan, but I like short lists. So here are five excellent illustrators, in no particular order.
Maurice Sendak
Everyone knows Maurice Sendak, whether or not they can link his name to his work. He's probably most popular for Where the Wild Things Are, but he's also the man responsible for In the Night Kitchen, my most treasured banned-book. As a child, I repeatedly checked this book out of the library and pored over its pages, lingering perhaps too long on the pages where Mickey was drawn without his clothes. Sendak is also to thank for Chicken Soup with Rice, another book full of terrific images and poems about soup. Can't be beat.
Mabel Lucie Attwell
Aside from having a really cool name, Mabel Lucie Attwell has a really recognizable style. I didn't grow up a fan of hers - I've only recently put her name to her work - but she's a great inspiration.
Margaret Tempest
I didn't know anything about Margaret Tempest when I bought a poster of her illustrated alphabet, but I'm glad to know now. She has a definite Beatrix Potter feel to her work, but I think that her creations are more human than Potter's.
Anton Pieck
Anton Pieck is an immensely talented illustrator who puts an incredible amount of detail into his drawings. I love looking at images like his and getting lost in the scene. I used to have a real problem with staring too long into detailed illustrations, but I believe it is artists like Pieck who gave me a desire to feed my imagination until it became nice and plump.
Arthur Rackham
Arthur Rackham may be my favorite on this list. He has illustrated nearly all of the "classic" fairy tales, and has such a haunting style that just blows me away. I had trouble choosing one image to best represent this man - and I would have even more trouble choosing a favorite.
Also check out Edward Gorey's
The Gashlycrumb Tinies. A child and an untimely death for each letter of the alphabet.