Liak was a Trill symbiont who died sometime in the late-8th century. Shortly after its fourteenth host died, Liak swam to the depths of the Caves of Mak'ala on planet Trill and, before Liak's own death, had its memories stored by the Annuated. In the year 2376, Ezri Dax briefly experienced some of Liak's memories courtesy of one of the Annuated. (DS9 - Worlds of Star Trek: Deep Space Nine novel: Trill: Unjoined)