Robert Michaelis von Olshausen (3 July 1835 – 1 February 1915) was a German obstetrician and gynecologist.
He was the son of Justus Olshausen (1800–82), a professor of Oriental languages at the University of Kiel.
In 1857 he obtained his doctorate from Königsberg, and afterwards served as an assistant to Eduard Arnold Martin in Berlin and to Anton Friedrich Hohl at the University of Halle.
In 1887 he returned to Berlin as successor to Karl Ludwig Ernst Schroeder as director of the university Frauenklinik.
He was publisher of the journal "Zeitschrift für Geburtshilfe und Gynäkologie", and with Johann Veit (1852–1917), he published Karl Schroeder's "Lehrbuch der Geburtshülfe" (from 1888, 10th to 12th editions, the last in 1899 as "Lehrbuch der Geburshülfte").