Rudolf of Zähringen (also Rudolph or Ralph) (c.1135–5 August 1191) was the archbishop of Mainz from 1160 to 1161 and prince-bishop of Liège. He was the son of Conrad I of Zähringen and Clemence of Luxembourg. In 1167, he became bishop of Liège, a position almost as secularly important as that of Mainz. As bishop, he supported his brother, Berthold IV of Zähringen. On 11 May 1188, he arrived at the Siege of Acre with an army. He died on the way back from the Crusade, at Herdern. He was buried in the monastery of Saint Peter's there.