Gregory IV (died 915) was the firstborn son of Duke Sergius II of Naples and successor of his paternal uncle, Bishop Athanasius, in 898, when he was elected dux, or magister militum, unanimously by the aristocracy.
According to the much later chronicler Leo of Ostia, he signed a pact with the prince of Benevento and Capua, Atenulf, and the Amalfitans and attacked and defeated the Saracens.
In 915, he joined the massive army of south Italian princes and the Byzantine strategos Nicholas Picingli and received the imperial title of patricius.
Gregory did not long live to enjoy the fruits of victory, he died within months, late in the year 915, and was succeeded by his firstborn son, John II, who had been present at the battle.
In 907 Gregory made a donation to the urban church of Saints Severinus and Sossus in Naples, which his forefathers had possibly founded.