Rudolf Otto von Ottenfeld was an Austrian military painter, a founding member of the Vienna Secession and a professor at the Academy of Fine Arts, Prague.

Ottenfeld was a student at the Academy of Fine Arts, Vienna under Carl Wurzinger and Leopold Carl Müller. He lived in Munich in 1883–93 and Vienna in 1893–1900. For the Sixth International Art Exhibition in Munich in 1892, he was selected as a juror. Ottenfeld's illustrations in a history of the Austrian army between 1700 and 1867 in 1895, which became a standard reference work on uniforms in the period.

He was a founding member of the Vienna Secession and sat on the Secession's working committee. The title page of the fourth issue of Ver Sacrum, the official journal of the Secession, was designed by Ottenfeld. After the death of Julius Mařák in 1899, Ottenfeld was appointed to the Academy of Fine Arts, Prague. Among his students in Prague was the painter and art restorer Zdeněk Glückselig. He spent thirteen years there as a professor, until his death.

Ottenfeld was noted as a creator of military art in Vienna. He painted several battle scenes, as well as soldiers in uniform, with a historical context.