Ex libris Fritz Waerndorfer (1903).
I could happily post things by the indefatigable Koloman Moser (1868–1918) all the time but he’s not exactly an unknown figure even if his work does get overshadowed by his colleague in the Vienna Secession, Gustav Klimt. This handful of ex libris plates almost all date from the Secession period, and include one for Adele Bloch-Bauer, a woman whose name is familiar these days for her being the subject of a very well-known Klimt portrait.
Ex libris Fritz Schwartz (1900).
Ex libris Rudolf Steindl (1900).