Dax character jug produced in Indonesia for Applause of Woodland Hills, California, in 1997. Dax is a xenomorphic character in the fictional Star Trek universe. The Dax life form is a symbiont-one that lives inside and bonds to Trill humanoid hosts. The first appearance of a Trill was in the episode "The Host" from the fourth season of "Star Trek: The Next Generation"; in that early version, the personality of the being was entirely that of Odan, the symbiont within the host, whereas the personalities of the Trills in "Star Trek: Deep Space Nine" are a blending of the symbiont Dax and its sequential Trill hosts. Two of Dax's hosts, Jadzia Dax and Ezri Dax, appear as major characters in "Star Trek: Deep Space Nine".