Jean Pierre Polnareff is the second to last addition to the Crusaders, who joined after he fought and was defeated by Muhammad Avdol.
Polnareff is the stereotypical "good-natured klutz". He is heroic and protective of those he loves, but is not very bright (although he has shown lots of cunning and strategy throughout the series). He is very impulsive and loud, and is quick to jump into action without considering the risk, character traits that have landed him in lots of trouble. However, he is sincerely dedicated to doing good, and is a good man who can watch his friends' backs. He also fancies himself as a ladies man, but his personality implies that he overestimates his actual prowess.
Out of all the characters in the series, Polnareff is the one who has the least problems showing his feelings, and he adds a lot of humor and warmth to what would otherwise be a pretty cold team (Kakyoin and Jotaro in particular are very cold characters). Indeed, while he may sometimes be seen as the comic relief of the series, Polnareff's companions appreciate his good nature and trust him to help them win when a tough battle arrives.
He went with Jotaro Kujo and Joseph Joestar to get revenge for his sister, who was raped and murdered by J. Geil. His Stand is the Silver Chariot.