Koloman Moser (1868-1918) was one of the leading lights of the Vienna Secession and probably the most versatile of the lot. He designed furniture, posters, stained glass windows and household objects besides doing a little painting. Moreover, the work he did was generally of very high quality (with an exception noted below).
Biographical information on Moser can be found here and here. There are books about him as well; check Amazon or another web site for details.
Here are a few examples of his work:
Gallery
For some reason Moser was not adept at painting, or so I think. This one is better than most, but still rather messy compared to the clean, well-designed posters, bookmarks and other graphic work he produced.