William Tutin Thomas (1829–1892) was a Canadian architect.

Born in Birmingham, England, he was the son of architect William Thomas.

His father emigrated with his family from England to live in Montreal, and there together they made many fine buildings, including some notable shopping arcades in Montreal, and many buildings in Old Montreal (such as the Dominion Block, the Recollet House, and the Caverhill Block).

He built many residential buildings for the upper middle classes of Montreal, notably the George Stephen House, later known as the Mount Stephen Club (1882–1884), and the house of Thomas Shaughnessy (1874–1875, which is now part of the Canadian Centre for Architecture.

He was a founding member of the Royal Canadian Academy of Arts.