Ranulf II (or Rainulf II, Italian: Rainulfo; died 30 April 1139) was the count of Alife and Caiazzo, and duke of Apulia. He was a member of the Italo-Norman Drengot family which dominated the Principality of Capua for most of the century between 1050 and 1150. Ranulf's wife, Matilda, was the sister of King Roger II of Sicily.
Ranulf II was the son of Robert, count of Alife and Caiazzo. and Gaitelgrima. His grandfather was Ranulf I of Caiazzo, a brother of Prince Richard I of Capua. His great-grandfather was Asclettin, count of Acerenza. Asclettin was a brother of the Ranulf Drengot, the first Norman fiefholder in Italy. As the third Ranulf in his family, Ranulf of Alife is sometimes called "Ranulf III".