(covers information from several alternate timelines)
Sometime before 2349, while Chakotay was a cadet at Starfleet Academy, he sparred with a Terrellian. He later recreated this in the holographic program "Chakotay Training Program 15-Beta". (VOY: "The Fight")
In 2371, Nog met three Terrellians who were visiting Deep Space 9 and who bragged about how great they were at dom-jot. Nog arranged a game, for himself and Jake Sisko, against the Terrellians for a strip of latinum per game, playing with double-back rules. (DS9: "Life Support")
In a scene cut from "All Good Things...", the USS Enterprise-D encountered five Terrellian transports, in an alternate timeline created by Q, that were holding position in the Devron system in 2370. The commander of the lead ship was named Androna, played by actress Martha Hackett. It was further implied in this scene that the Terrellians were Federation members, as they were ordered by Picard back to Federation space.