Sanji (サンジ, Sanji), born as Vinsmoke Sanji (ヴィンスモーク・サンジ, Vinsumōku Sanji) and also known as "Black leg" Sanji (黒足のサンジ, Kuro Ashi no Sanji), is a fictional character in the One Piece franchise created by Eiichiro Oda. He serves as the cook of Monkey D. Luffy's pirate crew, the Straw Hat Pirates.

A native to the North Blue, Sanji grew up as part of the Vinsmoke family under his father Vinsmoke Judge, king of the fallen Germa Kingdom, and mother Vinsmoke Sora. Judge sought to regain the family's long lost glory by creating the strongest army, using his expertise as a scientist to create hundreds of clones of his best soldiers. Blinded by the pursuit of power, he even experimented on his five children. Sora, who didn't like that they would practically become inhuman, tried to undo said experiments by taking a powerful drug. However, amongst them, only Sanji was affected by this, being the only one without any powers and with the ability to feel emotions; as such, Judge resented Sanji, deeming him a "failure" and favored his other, more "successful" siblings, who also treated Sanji as a punching bag due to his perceived inferiority.

After being locked up in a dungeon by Judge, who wanted to pretend he was never born, Sanji escapes to the Baratie, through the help of his sister, where he learns to cook under "Red Foot" Zeff and learns his fighting style, which is characterized by the use of legs in combat, leaving his hands for cooking. Following a battle against Don Krieg, Sanji joins the Straw Hats in order to fulfill his dream of finding the All Blue, a mythical sea said to have fish from around the world. Although his demeanor mostly consists of him being calm and collected, he is also shown to have a heavy attraction to beautiful women, as exemplified via the hearts in his eyes. His chivalrous nature also prevents him from attacking any women.