Waldemar of Brandenburg (German: Waldemar der Große) (c. 1280 – 14 August 1319, Bärwalde) was Margrave of Brandenburg-Stendal, the last from the Ascanian House.
He was a son of Conrad, Margrave of Brandenburg-Stendal and Constance, daughter of Przemysł I of Greater Poland. Waldemar was co-regent from 1302, and succeeded in 1309 as a guardian for his cousin Henry II, Margrave of Brandenburg-Stendal.
By the Treaty of Soldin (1309), Waldemar relinquished his claims on Pomerelia and Danzig to the Teutonic Order for a payment of 10000 silver Mark. The castle districts Stolpe and Schlawe remained with Brandenburg. These countries, however, were given, together with Rügenwalde, to Duke Wartislaw IV of Pomerania-Wolgast in 1317.
In 1316 he supported Stralsund against Denmark and thereby provoked a large coalition of Denmark, Sweden, Poland, Mecklenburg and the Welfs against himself. He held his position but in the end had to give up Stargard-Neubrandenburg at Mecklenburg. In 1319 Waldemar acquired for Brandenburg Zuellichau and Schwiebus.
Waldemar was the last governing member of the Brandenburg line of the Ascanian House. In 1309 he married Agnes of Brandenburg (1297–1334), a daughter of Margrave Hermann III. This marriage was childless.
With the death of Waldemar's ward Henry II the Brandenburg branch of the Ascanian House died off in 1320, and was succeeded by the Empire.
In 1348, an impostor dubbed "False Waldemar" successfully claimed that he was Waldemar, returning from pilgrimage to the Holy Land after somebody else had been buried in his place. Quickly gaining support due to rivalries, the Emperor reinvested him for about two years before "the last Ascanian" spend his remaining life at the court in Dessau.
| Preceded by John V |
Margrave of Brandenburg 1305–1319 |
Succeeded by Henry II |