Thon is a male Tchuukthai Jedi Master, introduced in Tales of the Jedi #3 (Dark Horse, 1993). His species is secretive to the point that the location of their world in the Unknown Regions is deliberately unrecorded, and his true form is not what visitors assume — an idea the comics use for a small, effective lesson about Jedi perception.
He matters as the teacher of Nomi Sunrider, and specifically as a Master willing to train a student who refuses the weapon. Thon is one of Star Wars' clearest early statements that the Jedi are not primarily swordsmen, delivered by a character shaped like a plated quadruped, on a swamp world, in a 1993 comic.
Catalogue entry. This figure has a verified record here rather than a full write-up — the encyclopedia labels its own depth instead of padding it.