Quinlan Vos is a Kiffar male Jedi Master from Kiffu. He began as an extra: a background figure glimpsed in the Mos Espa crowd in The Phantom Menace (1999), whom writer John Ostrander and artist Jan Duursema turned into a lead for Dark Horse's long-running Star Wars: Republic comics.
Psychometry
His defining ability is retrocognition — touch an object, perceive the memories of whoever handled it. That makes him the Order's best tracker and its most exposed one, because a Jedi who feels other people's experiences at second hand is a Jedi with a permanent open channel to the worst of them.
The undercover Jedi
In the Legends comics he spends years working inside Dooku's organisation, playing double agent so effectively that the Council itself stops being sure which side he is on. It is the most sustained treatment anyone has given the idea that the dark side is not a switch but a slow occupational exposure.
Canon: Dark Disciple
Current canon recovered him. He appears in The Clone Wars, and Christie Golden's Dark Disciple (Del Rey, 2015) gives him a canon version of the same story — sent to kill Dooku with Asajj Ventress's help, falling in love with her, and going considerably further into the dark than the mission required. The Legends comics run is far longer, but the canon novel is the sharper single text.
Reading note
Vos is the best available answer to a question the prequels avoid: what happens to a Jedi who is asked to do intelligence work by an Order whose entire ethic assumes you never lie?
