William of Ypres

William of Ypres (c. 1090 – 24 January 1164/1165 ), styled count of Flanders, was King Stephen of England's chief lieutenant during the English civil wars of 1139–54 (known as the Anarchy). He commanded a contingent of Flemish soldiers. He claimed the county of Flanders upon the death of Charles the Good on 2 March 1127/28.

Though no proof exists of his creation as Earl of Kent by King Stephen, chroniclers describe him as "possessing the county" and "having Kent in his custody". He exercised the same powers over this county as other earls over theirs; though he never adopted the comital (of a count or earl ) style.

He founded the Cistercian house of Boxley circa 1146.

Family
He was an illegitimate son of Philip of Loo, son of Robert I, Count of Flanders and Gertrude of Saxony. He was a claimant in 1119 to the title of Count of Flanders but lost the claim to Charles the Good; and again in 1127, when he lost to William Clito. The chronicle of Galbert of Bruges attributes his failure to his illegitimate birth. He sought the title again the following year (1128) after William Clito's death, but lost to Thierry of Alsace, who banished him from Flanders in 1133.