Reginar IV, Count of Mons, in Hainaut, (c. 950-1013) was the son of Reginar III and Adela. His father died in exile in Bohemia in 973.

History

His father, Reginar III, was exiled in 958 as a rebel by Otto I, Holy Roman Emperor. Hainaut was held after then by Godfrey I, Duke of Lower Lorraine, but Reginar IV claimed that Mons in Hainaut had been his father's.