Iyothee Thass (20 May 1845 – 1914) was a prominent Tamil anti-caste activist and a practitioner of Siddha medicine.
He famously converted to Buddhism and called upon the Paraiyars to do the same, arguing that this was their original religion.
He also founded the Punchmar Mahajana Sabha in 1891 along with Rettamalai Srinivasan.
Punchamas are the ones who do not come under Varna system; they are called as Avarnas.
"Iyothee Thass" is the most common Anglicized spelling of his name; other spellings include Pandit C.