A colonist was an individual who lived in a colony.
Jovain Pallis was a colonist on Mars. He murdered two of his crew mates, Marissa and Uther. The Second Doctor took him to an uninhabited planet in the TARDIS and left him there. (PROSE: Dust)
Several humans, led by John Robert Ashe, were colonists on Uxarieus after leaving Earth in 2471. (TV: Colony in Space)
Laroq was a Phoenix colonist who met the Fifth Doctor, Erimem and Peri. (AUDIO: Three's a Crowd)
Ted Henry was a human colonist on Teuba. At the time of the Sixth Doctor and Evelyn Smythe's visit, he was the president of the colony. (PROSE: The Diplomat's Story)
Dimitri Molokomme was a colonist on Yemaya 4. He was in charge of agriculture for the colony. (PROSE: SLEEPY)
Sharma was a human colonist on Ramosa. She used to run the recycling plants. (AUDIO: The Reviled)
The Master once gave a group of jobless Earth colonists "job placements" in the Sabre-Toothed Gorilla House of the Galactic Zoo as "charity work" - the Master actually just fed them to the Sabre-Toothed Gorillas. (PROSE: A letter from the Master)
Upon landing on the Mondasian colony ship, the Twelfth Doctor and Missy suspected that the ship had been on-route to collect its colonists before passing too close to a black hole. (TV: World Enough and Time)
In an early Time Lord colonisation effort, the colonists' regenerations drew in biodata from the local environment, metamorphosing them into ever more alien forms. When this caused the colonists to be targeted by regressive policies on Gallifrey, the Fugitive Doctor evacuated them all to a new world. (COMIC: Origins)