Adolph II, Prince of Anhalt-Köthen (16 October 1458 – 24 March 1526, in Merseburg), was a German prince of the House of Ascania and ruler of the principality of Anhalt-Köthen. A Roman Catholic Bishop of Merseburg, he remained until his death a staunch opponent of Martin Luther.
He was the fifth and youngest son of Adolph I, Prince of Anhalt-Köthen, by his wife Cordula, daughter of Albert III, Count of Lindau-Ruppin.
In 1471 Adolph began his studies at the University of Leipzig and in 1475 was elected Rector. Because he and his brothers had decided to become priests, their father Adolph I drew up a succession contract with the Anhalt-Dessau branch of the House of Ascania, headed by George I, Prince of Anhalt-Dessau, to secure the existence of the principality. The contract stipulated that Adolph I would rule jointly with George's son Waldemar VI, and that Adolph I's half-brother Albert VI was to become co-ruler with Waldemar after Adolph's death. Upon the death of Albert VI, Adolph II and his brother Magnus succeeded their uncle as co-rulers of Anhalt-Köthen with their cousins Philip and Waldemar VI. Adolph used the title "Lord of Zerbst" to identify the portion of the principality in which he resided. Despite his spiritual office, Adolph participated in the government of his principality for several years; only in 1508 did he formally renounce his rights along with this brother Magnus.
In 1488 Adolph II became Provost of Magdeburg Cathedral, then was ordained as a priest two years later (in 1490). In 1507 was accepted by Bishop Thilo of Merseburg as his Coadjutor and succeeded him in 1514 as Bishop of Merseburg.