Coleman Trebor was a Jedi Master during the declining days of the Old Republic, during the threat of a separatist faction. Coleman was a male Vurk from the planet of Sembla, a planet covered by warm seas and slowly forming continents, and the Vurk were an amphibious and nomadic species, and considered primitive by most of the galaxy. With eyes that could see in all directions and a crest atop his head giving him a height of over two meters, Coleman Trebor was an imposing figure. After he attained the rank of Jedi Master, Coleman served on the Jedi Council, replacing Yarael Poof after his unfortunate death.
As a Jedi Master, Coleman settled many interplanetary disputes without violence and was considered to be an excellent negotiator. However, like all Jedi Coleman possessed his own lightsaber, which he used whenever it was necessary. One of those necessary times was when Count Dooku, leader of the Separatists, captured fellow Jedi Knight Obi-Wan Kenobi and Anakin Skywalker, and was using the planet Geonosis to build up an army of droids to launch an attack against the Republic.
When the Jedi learned of this, Jedi Masters Mace Windu and Yoda made plans to go to Geonosis to rescue Obi-Wan and Anakin and launch a preemptive strike against the droid army, Mace with the remaining Jedi and the Jedi Temple, and Yoda with the newly discovered Republic Army. Coleman was one of 200 Jedi to go to Geonosis, but unfortunately this mission did not end peacefully. Luring the Jedi into a trap, Count Dooku surrounded the Jedi with thousands of battle droids, and soon the mission turned into a fight for survival. It was obvious that Count Dooku had to be stopped and during the fight Coleman managed to make his way to Dooku's location, a spectator box high up in a Geonosis arena, and confront him.