Fujiwara Sumitomo (died 941, Iyo Province, Japan) was a notorious Japanese pirate leader. Originally a government official, he was dispatched by the court to eliminate pirates plaguing the Inland Sea, which connects central and south Japan. A traitor to the trust placed in him, Sumitomo became the leader of the pirates and other dissident local bands and thereby gained control of most of the strategic areas along the waterway before he was defeated in 941. His actions helped to weaken Japan’s central government.