A Class-M planet of humanoid natives, where two warring factions were located on its two major continents. One developed to a point approximating late 20th-century Earth and unleashed a deadly biological plague on their enemy while infecting themselves as well. Some Tarellians escaped to live elsewhere but infected the planets they joined; others were hunted down when they tried to live in isolation.

The last such Tarellian ship was thought to have been destroyed in 2356 by the Alcyones, but one turns up at Haven in 2364.