Qui-Gon Jinn is a human Jedi Master, introduced in Star Wars: Episode I The Phantom Menace (1999) and played by Liam Neeson. He was trained by Dooku, he trained Obi-Wan Kenobi, and he never sat on the Jedi Council — a fact the films treat as a character note and the novels treat as a thesis. He belongs, on this site, to the Fall of the Jedi.
The maverick reading
The easy version of Qui-Gon is "the rebel Jedi." The more interesting version, which the prose fiction has pursued since 2019, is that he is the only senior Jedi still practising the Order's own stated beliefs. The Council has become an arm of Republic governance. Qui-Gon still thinks the Force is something you listen to rather than something you administer. That is not rebellion; it is orthodoxy that has outlived its institution.
In the books
Claudia Gray's Master & Apprentice (Del Rey, 2019) is the essential text. It puts him eight years before the invasion of Naboo, offers him a Council seat he does not want, and builds the whole novel around the question of whether prophecy is knowledge or superstition — with Qui-Gon on the unfashionable side of the argument.
The afterlife
John Jackson Miller's The Living Force (Del Rey, 2024) catches the same argument a year before Naboo, with the whole Council out in the field for once. His death at the end of The Phantom Menace is the hinge of the prequel trilogy: it hands Anakin Skywalker to a teacher who is not ready, and it removes the one voice that might have argued for a different approach. Everything that follows is, in part, a consequence of that gap.