- Curzon Dax
- Jadzia Dax
- Ezri Dax
- Illa Dax
- Lenara Kahn
- Gray Tal
- Ohk
- Kareel Odan
- Most were distinguished by two rows of dark spots, which went all the way down each side of their bodies
- Minority didn't have spots but had ridges on their foreheads
- Typically joined in their early- to mid-twenties
- Joining occurred surgically, placing the symbiont in the host's abdomen;
- It connected neurologically & biologically with the host
- After 93 hours of joining, symbiont & host could not survive long without one another
- Retained the memories of all previous hosts, shared with each new one
- Symbiosis Commission oversaw the joining of the Trills & symbionts;
- Law forbade reassociation between hosts that had been romantically involved;
- Zhian'tara: a ritual for a joined Trill meets the previous hosts of the Symbiont
- Only a certain number of Trill could be joined
- Joining dates back to the 12th century, not widely known before 2367
- The Burn resulted in the depletion of the symbiont & joinable-host population
