Usopp is the sniper of the Straw Hat Pirates, and the former Captain of the Usopp Pirates. When Usopp was first introduced, he was often (comically) labeled as the "Liar" of the Straw Hat Pirates, due to the "Uso" (うそ) in his name meaning "lie" or "falsehood". He was born in Syrup Village, and was first mentioned by Yasopp, his father. He was officially the third (unofficially fourth) member of the crew, and the third to join, and, including Nami and Robin, also the third to rejoin, doing so at the end of the Post-Enies Lobby Arc. His bounty of 30,000,000 is credited to his alias and alter-ego "Sogeking". He is also considered one of the "weak" trio of the crew, along with Nami and Chopper. After awakening Kenbunshoku Haki, he became the fourth member of the Straw Hat crew to demonstrate and use a form of Haki.
Usopp is a slim teenager with medium-length black curly hair and a long nose, which is apparently an allusion to Pinocchio (a wooden boy from a story of the same name who possessed a nose that would stretch after he lied). Usopp inherited his famous nose from his mother, while the rest of his face closely resembles his father's. During the Straw Hat separation, after landing in the Boin Archipelago, Usopp grew obese from overeating.
He usually wears an olive green plaid bandanna, a blue and white striped armband on his left arm, along with special sniper goggles (he also has a pair of clear rectangular goggles that he sometimes wears in situations where he does not have his sniper goggles, like when he first met the Straw Hat Pirates or when his sniper goggles were stolen by Mr. 2), brown overalls with a white sash and no shirt underneath (although he wore a murky green shirt during the Skypiea Arc).
He also carries with him a yellow satchel, which he stores all his tools and gadgets in.
After the two year timeskip, Usopp has increased muscle hypertrophy and has grown his hair out. He has become "manlier" and is slightly taller than before.
Usopp now has a new pair of goggles around his neck (his sniper goggles weren't shown) and has some headphones or ear protectors on. He also now has a little goatee along with a new white suncap he wears on his head. He also has a new pair of rolled-up yellow pants with red suspenders, and a pair of boots.
His trademark yellow satchel has been replaced with a red one, but he still has his blue and white striped wrist band on his left arm.
During the Dressrosa Arc, he wore an orange open jacket with a ring of circles on the arms and a red cap which has a pointy stub on the end, which he used to make the Dwarves believe he was a descendant of Noland.