Then check out the Artcyclopedia.
I'm not sure it's a good name for it; it's not an encyclopedia, though it does list some info about the artists it has -- as you can see here for a sample.
But (as you can also see at the link) what it really has lots and lots of are links to where images of the artist's paintings are online. At commerical galleries. At museum and public art gallery websites. At online art archives.
Also it lists articles about the artist, but I've never checked out those. I've used the site to find images. Sometimes I've stumped it as I have been looking for obscure artists, but it does have an amazing assortment of names.