Siegfried I, Prince of Anhalt-Zerbst, was a German prince of the House of Ascania and ruler of the principality of Anhalt-Zerbst.
Background
He was the youngest son of Henry I, Count of Anhalt (who was raised to the rank of prince in 1218), by his wife Irmgard, daughter of Hermann I, Landgrave of Thuringia. After the death of his father in 1252, in accordance with the family law of the House of Ascania, the sons of the late Prince divided his lands.
Career
Siegfried received Zerbst. His style Count of Köthen-Dessau (used from 1253) derived from the territories he received as his inheritance. In 1247, after the death of Henry Raspe, the last Landgrave of Thuringia from the Ludowinger Dynasty and the resulting War of the Thuringen Succession, the young Siegfried occupied the Palatine County (German: Pfalzgrafschaft), by right of his mother Irmgard.
Later he renounced the county in favor of the House of Wettin in exchange for a monetary compensation.
In 1290 Siegfried renounced his rule to become a preaching monk (German: Predigermönch).