Marinus II (died 992) is the Duke of Naples from 968 to his death.

He is the son and successor of John III and brings Naples back into the Byzantine fold, receiving the title eminentissimus consul et dux, atque imperialis anthipatus patricius.

In 970, Marinus does homage for his duchy to the patrician Eugene after the imprisonment of Pandulf Ironhead.

He then participates in the siege of Capua.

He devastates the surrounding countryside and takes an enormous booty before an army of Otto the Great forces the Greeks to retreat.

In 974, Marinus allies with Manso I of Amalfi and Landulf of Conza to depose Gisulf I of Salerno.

They are defeated, however, by the intervention of Pandulf Ironhead.

On November 4, 981, the Emperor Otto II is in Naples, probably with the permission of Marinus, who is moving away from his pro-Byzantine policy.

He dies in 997 and is succeeded by his son Sergius III.

In 975, Marinus makes a donation to the urban church of Saints Severinus and Sossus in Naples.