The star of the first three Ace Attorney games (and an important presence in the fourth), Phoenix Wright is a defense attorney with a passion for justice. Even when all seems lost, Phoenix Wright will fight to ensure that his clients are proven innocent.
(Spoilers for the series follow)
Originally an art student, Phoenix Wright was inspired to switch to law when his later-mentor Mia Fey defended him in court, reminding him of another time when his elementary school friend Miles Edgeworth (later to become a prosecutor and Wright's rival) defended Wright from the rest of his class when they accused him of stealing Edgeworth's lunch money.
Throughout his years as a lawyer, he became known for his ability to turn around a court case at a last second, going up against such famed lawyers as Miles Edgeworth, Manfred von Karma, Franziska von Karma, and Godot. His ability was in part thanks to the Magatama, a mystical gem given to him by his friends the Feys, that enabled him to break the locks on someone's psyche and find out their secrets.
Eventually, however, his reign of the court room came to an end, when he unknowingly presented falsified evidence and was disbarred. Over the years, he adopted a daughter, Trudy, and turned his law firm into a talent agency to help her market her abilities as a magician.
He was dragged back into the court room when he was once again accused of murder. This time, he picked newbie defense attorney Apollo Justice to defend him. When Justice succeeds, Wright expands his talent agency to once again include a law firm and hires Apollo to work for him. Of the course of months, he helps Justice become a better attorney, until eventually Apollo manages to clear his name from the case that disbarred him. He is considering retaking the bar exam, but hasn't made a decision yet.
During the events of Apollo Justice: Ace Attorney, he also pushed for reform in the court system, where a jury would decide the verdict instead of just a single judge. This culminated in the final case being decided by jury.