Baldwin IV of Flanders (980 – May 30, 1036), known as the Bearded, was Count of Flanders from 988 until his death. He was the son of Arnulf II of Flanders.

Other than his predecessors Baldwin turned his attention to the east and north, leaving the southern part of his territory in the hands of his vassals the counts of Guines, Hesdin, and St. Pol.
To the north of the county Baldwin was given Zeeland as a fief by the Holy Roman Emperor Henry II, while on the right bank of the Scheldt river he received Valenciennes (1013) and parts of the Cambresis and Hainaut.

In the French territories of the count of Flanders, the supremacy of the Baldwini remained unchallenged. They organized a great deal of colonization of marshland along the coastline of Flanders and enlarged the harbour and city of Brugge.

Baldwin first married Ogive of Luxembourg, by whom he had a son and heir Baldwin V. He later married Eleanor of Normandy, daughter of Richard II of Normandy, by whom he had at least one daughter Judith. This daughter married Tostig Godwinson, Earl of Northumberland.[1] These family connections demonstrate the political interests of the Flemish counts, both in the Kingdom of France, England and the Holy Roman Empire.

His granddaughter, Matilda of Flanders, would go on to marry William the Conqueror, therefore starting the line of Anglo-Norman Kings of England.