Adolf III of Schauenburg (German: Adolf von Schaumburg) (1511–1556) was the Archbishop-Elector of Cologne from 1547 to 1556.
Adolf of Schauenburg was born on January 19, 1511 and baptized on 3 February. He was the son of Jobst I, Count of Holstein-Schauenburg and his wife Maria of Nassau-Dillenburg.
As a younger son, Adolf was groomed for a life in the church from a young age. From 1522 he studied at Leuven. He became a canon of Liège Cathedral on September 2, 1528, and then provost of the cathedral on May 30, 1533. In 1529, he also became a canon of Mainz Cathedral and, on December 23, 1529, of Cologne Cathedral. He became dean of St. Gereon's Basilica, and then its provost in 1533.
With his father's death in 1531, Adolf returned to Schaumburg to act as his younger brothers' guardian. He played a role in the governance of Schaumburg until 1544.
In the early 1530s, the Archbishop of Cologne, Hermann of Wied, grew increasingly sympathetic to the Protestant Reformation. To try to curb the archbishop's influence, on December 17, 1533, the cathedral chapter of Cologne Cathedral elected Adolf to be the coadjutor bishop of Cologne. He was to be a conservative counterweight to Hermann's attempted reforms.