William IV, Count of Weimar (died 1062) wasMargrave of Meissen from 1046 until his death.

He was the eldest son of CountWilliam III of Weimar from his second marriage with Oda, a daughter of MargraveThietmar of the Saxon Eastern March. He becamecount ofWeimar andOrlamünde inThuringia upon the death of his father in 1039. William was appointedcount palatine ofSaxony in 1042.

When in 1046 MargraveEckard II of Meissen died and willed hismargraviate to EmperorHenry III, the emperor promptly granted it to William, who, through the second marriage of his mother Oda, also received the Thuringian estates of his stepfather MargraveDedi II of Lusatia. Thereby, he united the territory held by late Margrave Eckard II of Meissen under his rule.

William remained a loyal supporter of the rulingSalian dynasty and, upon the death of the emperor in 1056, backed theregency of his widow EmpressAgnes of Poitou. He was highly in favour with the empress, who gave him command alongside Bishop Eberhard ofNaumburg, of the army in the 1060 campaign in support of KingAndrew I of Hungary against his brotherBéla I. According to the chroniclerLambert of Hersfeld, instead of waiting for an assistingBohemian contingent under DukeSpytihněv II, they immediately attacked Béla's forces and the German army was soon in retreat. While King Andrew was deadly wounded, William and Bishop Eberhard were captured at theBattle of the Theben Pass nearMoson (Wieselburg). However, Béla's sonGéza, impressed by William's courage, induced his father to not only release him, but give him his daughter Sophia in marriage.

Meanwhile, William had returned to Germany. When in 1062 he again proceeded to Hungary to marry Sophia, however, he fell ill and died on his journey. Sophia married his nephew MargraveUlric I of Carniola instead. The Meissen margraviate passed to William's younger brotherOtto I.

• ADB:Wilhelm (Graf von Weimar-Orlamünde) at GermanWikisource.

• Margraves of Meissen
• Landgraves of Thuringia
• 1062 deaths
• 11th-century counts in Europe
• 11th-century German nobility
• House of Weimar

• Pages where birth or death is being automatically determined
• Year of birth unknown