A humanoid people nearly wiped out by biological warfare whose last survivors drifted through space aboard a plague ship.
The Tarellians are a humanoid species whose homeworld was devastated by biological warfare. The resulting plague killed most of the population, and the few survivors fled into space, where other worlds feared them and refused to take them in.
In Haven, a Tarellian ship approached the planet Haven, whose people dreaded infection. Aboard was Ariana, who had shared telepathic dreams for years with Wyatt Miller, the man arranged to marry Deanna Troi. Wyatt, a doctor, chose to beam over and join the Tarellians so that he could treat them and be with Ariana.