Qui-Gon Jinn was well-known in the Jedi Order as a maverick and even a Gray Jedi for his conflict with the Jedi Council. He was nevertheless a wise and talented Jedi who had plenty to teach to other members of the Order -- even Grand Master Yoda.
Early Life and Apprentices
Born in 92 BBY, Qui-Gon was brought to the Jedi Temple as an infant, like most Jedi, to be trained in the Force. When he was ten, he became Count Dooku's Padawan and trained to be a Jedi Knight.
(Dooku later left the Jedi Order and became a Sith.)
As a Knight, Qui-Gon discovered a young Force-sensitive boy, Xanatos, the son of the governor of the planet Telos IV. Although Xanatos was older than most children when they came to the Jedi Temple, Qui-Gon believed he could still be trained. Qui-Gon trained one Padawan, Feemor, to Knighthood before becoming a Jedi Master, and then took Xanatos as his next Padawan. The apprenticeship ended in tragedy when Xanatos turned to the dark side, tempted by his father's power and wealth. After Qui-Gon was forced to kill the governor, Xanatos vowed revenge.
Qui-Gon was reluctant to take another Padawan until nearly a decade later, when Yoda convinced him to take a chance on thirteen-year-old Obi-Wan Kenobi. The master/apprentice relationship was rocky at first; both Qui-Gon and Obi-Wan were strong personalities and well-known for their rebellious streaks. Eventually, though, the bond between them strengthened, and they began to feel like father and son.
In the Prequel Trilogy
Episode I: The Phantom Menace
Obi-Wan and Qui-Gon were sent to Naboo in 32 BBY to negotiate with the Trade Federation. After negotiations failed, they escaped with Queen Amidala and made an emergency landing on Tatooine. There Qui-Gon discovered Anakin Skywalker, a nine-year-old slave with an unprecedented potential in the Force.
Convinced that Anakin was the Chosen One who would bring balance to the Force, Qui-Gon brought him back to Coruscant to present to the Jedi Council. Despite the Council's misgivings, Qui-Gon wouldn't back down. He insisted that Obi-Wan was ready to face the Trials to become a Jedi Knight -- leaving Qui-Gon free to take another apprentice -- and, when this ploy failed, instructed Anakin to simply observe him, learning indirectly from his practice as a Jedi.
But Qui-Gon had little time to train Anakin, officially or not; he died in a duel with the Sith Lord Darth Maul. With his dying breath, Qui-Gon told Obi-Wan to train Anakin.
Episode II: Attack of the Clones and Episode III: Revenge of the Sith
Qui-Gon survived as a Force ghost; although he no longer had a visible or physical body, his personality remained intact, and he could communicate with other Jedi. He tried, unsuccessfully, to prevent Anakin from slaughtering the Tusken Raiders who killed his mother.
After the fall of the Republic and the Jedi Order, Qui-Gon's spirit took Yoda as an apprentice, teaching the Jedi Master how to preserve himself as a Force ghost. He later taught the same technique to his old Padawan, Obi-Wan.
Behind the Scenes
Qui-Gon's communication with Yoda was cut from the Revenge of the Sith movie due to time constraints, along wih a number of other side plots (such as Padmé's role in the early formation of the Rebellion). The scene appears in the Revenge of the Sith novelization, however, and is mentioned in several other Expanded Universe sources.
Qui-Gon was portrayed by Liam Neeson in The Phantom Menace and Attack of the Clones. Fred Tatasciore voiced the character in Star Wars: Clone Wars, and James Warwick provided the voice in the video game Star Wars: Galactic Battlegrounds.