William Tassie (10 May 1815 – 21 November 1886) was an Irish-Canadian educator.
In 1851, he founded the Galt Grammar School and served as its headmaster until 1881.
He later became the principal at Peterborough Collegiate Institute.
Tassie was opposed to efforts in Upper Canada to reform the education system to focus on practical education, and was an advocate of a classical education.