Trevallyn is a suburb of Launceston, in the north of Tasmania, Australia.
It is located on the north western part of the city (west of the Tamar River and north of the South Esk River). It is the location of the Cataract Gorge and the Trevallyn Dam. It was the suburb in which Sir Benjamin Gill OAM called home while he lived at his home in Whitford Grove. The novelist, Katharine Susannah Prichard, lived there as a child.
The name of the suburb spelled backwards, Nyllavert, can be found on postal records and lists of localities; the local post office used to carry this name in the 1930s. Despite the place name no longer existing and not being officially gazetted, the name still appears in many lists and indexes of localities.