Sergius VI (died 1107) was the magister militum and duke of Naples from 1077 to his death.
He was the son of the Neapolitan senator John, and succeeded his uncle, John's elder brother, Sergius V. His sister Inmilgia married Duke Landulf of Gaeta.
[2] He apparently gave aid to the Norman prince Jordan I of Capua when the latter broke his alliance with Pope Gregory VII and did homage for his principality to the Holy Roman Emperor Henry IV.
The pope wrote to Prince Gisulf II of Salerno asking him to persuade Sergius to break off his support for Jordan and Henry.
[1] He was succeeded by their son, John VI, whom he had made co-ruler in 1090.