Siegfried I, Prince of Anhalt-Zerbst

Siegfried I, Prince of Anhalt-Zerbst (b. ca. 1230 – d. Köthen, 25 March 1298), was a German prince of the House of Ascania and ruler of the principality of Anhalt-Zerbst.

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. 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). As a result, his eldest son Albert became the new ruler of Zerbst, although the former prince retained his rank until his death.

On 17 October 1259, Siegfried married Katharina (Karin), daughter of Birger Magnusson, later known as Birger jarl, Regent of Sweden, by his wife Princess Ingeborg Eriksdotter of Sweden, sister of King Eric XI of Sweden. At the time of the wedding, the bride's older brother was King Waldemar of Sweden by right of their mother. They had ten children:

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