Trill is a type of vibration; it may refer to:
- trill (music), a type of musical ornament
- trill consonant, a type of sound used in some languages
- Trill, a sound similar to the musical ornament made by animals including the Maine Coon cat, numerous varieties of bird and the Golden Lion Tamarin.
In fiction:
- Trill (Star Trek), two symbiotic races of aliens in the fictional Star Trek universe
- Trill, an infant NetNavi from the MegaMan Anime
- Trill, a humanoid in the MUD Lusternia, Age of Ascension
In music:
In computer networking:
- TRILL , Transparent Interconnection of Lots of Links (IETF defined protocol)
In marketing:
In games:
In pets:
- An Australian Brand of Bird Seed