Henry Thomas Duffy KC (May 29, 1852 – July 3, 1903) was a Canadian politician.

Born in L'Avenir, Canada East, the son of John Duffy and Mary Ann Mountain, Duffy received a Bachelor of Arts degree in English literature in 1876 and a Bachelor of Laws degree in 1878 from McGill College.

Entering politics, he ran unsuccessfully as the Liberal candidate for a seat in the Legislative Assembly of Quebec in an 1889 by-election held in the electoral district of Brome.

In 1894, he was elected mayor of Sweetsburg, a post which he held for some time.

In 1900, he was made provincial treasurer in the cabinet of Simon-Napoléon Parent.