Thomas Allin (1838–1909) was an Anglo-Irish clergyman, a writer on Universalism, also known for botanical research.
- Race and Religion: Hellenistic Theology: its Place in Christian Thought 1900
- Universalism Asserted (1905) - J. W. Hanson recounts that this work started when Allin found a copy of Hosea Ballou's history of Universalism in the British Library and was led to a study of patristic literature.
- rewritten by Mark T Chamberlain, "Every Knee Shall Bow", privately published.
In his activity as naturalist he had Isaac Carroll (1828–1880) as collaborator. His surveys resulted in The Flowering Plants and Ferns of the County Cork (1883)
- Crockford's Clerical Dictionary
- C., J. [Coleman, James], A County Cork botanical author, Rev. Thomas Allin, Journal of the Cork Historical and Archaeological Society, Ser. 2, Vol. XXII, p. 91, 1916