Baldwin II (1056-1098) was count of Hainaut from 1071 to his death. He married Ida of Louvain (a sister of Godfrey I, Duke of Lower Lorraine) in 1084. Baldwin joined the First Crusade and was sent back to Constantinople with Hugh of Vermandois after the siege of Antioch in 1098, to seek assistance from Byzantine emperor Alexius I. However, Baldwin disappeared during a raid by the Seljuk Turks in Anatolia, and was presumably killed.

See also: Counts of Hainaut family tree