Baldwin IV (980 – 30 May 1035), called the Bearded, was the count of Flanders from 987 until his death.
Baldwin IV was the son of Count Arnulf II of Flanders (c. 961 — 987) and Rozala of Italy (950/60 – 1003), of the House of Ivrea. He succeeded his father as Count of Flanders in 987, 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 as well as Saint-Omer and the northern Ternois (1020). In his French territories, the supremacy of Baldwin remained unchallenged. A great deal of colonization of marshland was organized along the coastline of Flanders and the harbour and city of Brugge were enlarged.
Baldwin first married Ogive, daughter of Frederick of Luxembourg, by whom he had a son and heir, Baldwin V (1012 – 1067). In 1028 he arranged the marriage of his son Baldwin V with Adela of France, daughter of the French king Robert II of France. Two years later Baldwin V rebelled against his father.
Baldwin later married Eleanor, daughter of Richard II of Normandy, by whom he had a daughter, Judith (1033 – 1094).