Ranulf II (also known as Ranulf de Gernon) (1099–1153) was an Anglo-Norman potentate who inherited the honour of the palatine county of Chester upon the death of his father Ranulf le Meschin, 3rd Earl of Chester. He was descended from the Counts of [Bessin] in Normandy.
In 1136 David I of Scotland invaded England as far as Durham but was forced by Stephen of England to negotiate treaties that involved granting Ranulf's lands to Scotland. Ranulf allied himself to Matilda to further his cause. He took Lincoln Castle in 1141, which was retaken by Stephen in a siege in which Ranulf was forced to flee for his life. Ranulf enlisted the help of Robert, 1st Earl of Gloucester to retake the castle and succeeded when King Stephen surrendered to him at Lincoln. Whilst Matilda ruled England, Stephen's queen Matilda of Boulogne managed to defeat Ranulf and his allies at Winchester, which eventually resulted in Stephen being able to resume the throne.
Ranulf was born in Normandy at the Château Guernon, around 1100. He was the son of Ranulf le Meschin, 3rd Earl of Chester and Lucy of Bolingbroke, who were both significant landowners with considerable autonomy within the county palatine. His father had begun a new lineage of the earldom of Chester. Ranulf married Maud, daughter of Robert, 1st Earl of Gloucester and inherited the earldom in 1128. Three years later he founded an abbey in North Wales, colonised by monks from the Norman Congregation of Savigny.