Jedi Master Liam Dentiri is one of the most easily recognised Jedi on Tython. Liam Dentiri was the Jedi Order’s combat droid designer and architect of the Mark I, II, III Combat Droids that many, if not all Jedi Padawans and Knights trained their saber and force skills against on Tython as learners.
Two of perhaps the Jedi Order’s most infamous Jedi of the Old Republic era, the Barsen’thor (Jedi Consular) and the Hero of Tython (Jedi Knight) battled all four Marks of training droid at the request of Master Dentiri in order to test the effectiveness of the droids which had been programmed to follow Imperial combat droid battle effectiveness.

As the years went by, Master Dentiri would remain on Tython as the rest of the galaxy moved around him. Using the knowledge that he had learned from how the Barsen’thor and Hero of Tython had defeated his droids, he was able to fine tune them with an array of new utilities such as electric discharges, shielding and self destruct capabilities.
Dentiri himself would also go on to construct a dual-bladed Cyan lightsaber and learn how to camoflage himself using force stealth.

In 16 ATC, the Revanites tricked both the Republic and Empire into attacking each others force homeworld simultaniously. While many Jedi were away sacking Korriban, only a small force was present on Tython when the Sith Empire attacked. Master Dentiri locked the front of the Jedi Temple with a laser gate and called upon his upgraded droids to aid him in holding off the Imperial invaders. While he fought bravely against the Sith, Liam Dentiri would perish at the hands of the Empire, allowing the invaders to enter the Temple and take it for themselves.

Sources:

Combat Leadership Tython Quests – Star Wars the Old Republic
Assault on Tython Story (Imperial Version) – Prelude to Shadow of Revan