In 2370, while en route to Iyar, Jean-Luc Picard and his pilot, Voval, crash landed on a class M planet, where Picard discovered a Terellian freighter which had crashed there several years before. (TNG: "Liaisons")
This species is also briefly mentioned by the Doctor to Seven of Nine when he was explaining the new neural patterns had surfaced in her brain. Among them were Vulcan, Human, Klingon, and Terellian. (VOY: "Infinite Regress")
The Terellians are also mentioned in Voyager season 7 episode 3, "Drive" as a competing species in the race by Neelix immediately after the race resumes after an act of sabotage is resolved and the race resumes. It is not known if they are the same Terellians as from the alpha quadrant, but it is more likely to be a coincidence.