Rudolf Robert Maier (April 9, 1824 – November 7, 1888) was a German pathologist who was a native of Freiburg im Breisgau.
He studied medicine at the University of Freiburg, where one of his instructors was orthopedist Louis Georg Friedrich Stromeyer (1804–1876). He furthered his medical training in Vienna with Carl Rokitansky (1804–1878), Joseph Hyrtl (1810–1894) and Josef Skoda (1805–1881), and in Würzburg under Rudolf Virchow (1821–1902). Afterwards, he returned to Freiburg where he became an associate professor in 1859. Later he became a full professor, and in 1864 founded the first institute of pathological anatomy at Freiburg.
With Adolf Kussmaul (1822–1902), Maier provided the first comprehensive description of periarteritis nodosa, which is sometimes referred to as Kussmaul-Maier disease. The two doctors described their findings in the inaugural edition of the journal Deutsches Archiv für klinische Medicin, which was co-founded by Friedrich Albert von Zenker (1825–1898) and Hugo Wilhelm von Ziemssen (1829–1902). Among Maier's written works were biographical treatises on 16th century physicians, Johannes Schenck von Grafenberg (1530–1598) and Michael Servetus (1511–1553).