His seminal works "Celtic Myths and Legends" and "The High Deeds of Finn Mac Cumhail" are widely hailed as the best representation and description of all the legends, myths and spiritual history of all Celtic peoples of Ireland, Britain, and Wales.
Approximately 168 books are associated with Rolleston, some as writer or editor. These are the more prominent works; publication dates listed if known.
- The Teaching of Epictetus (1888)
- Life of Gotthold Ephraim Lessing (1889)
- Tannhauser: a dramatic poem by Richard Wagner; translated by T. W. Rolleston; illustrated by Willy Pogany. (1900)
- A Treasury of Irish Poetry in the English Tongue by Stopford A. Brooke & T. W. Rolleston (1900)
- Parallel Paths: a study in biology, ethics, and art (1908)
- The High Deeds of Finn Mac Cumhail (1910)
- Celtic Myths and Legends also entitled Myths & Legends of the Celtic Race (1911), Reprints (1917, 1990)
- The Illustrated Guide to Celtic Mythology. London: Studio Editions, (1993) (Based on: Myths & Legends of the Celtic Race)
- Parsifal or, The Legend of the Holy Grail, retold from ancient sources with acknowledgement to the "Parsifal" of Richard Wagner (1912)
- The tale of Lohengrin, knight of the swan by Richard Wagner and T. W. Rolleston; illustrated by Willy Pogany (1913)