Thomas Merritt Cayley (18 August 1878 – 30 May 1933) was a Liberal party member of the House of Commons of Canada.
He was born in East Oxford Township, Ontario and became an insurance agent, school principal and teacher.
Cayley attended secondary school at Norwich and normal school in London, Ontario.
He was principal of Norwich Continuation School for four years.
Cayley died on 30 May 1933 before completing his term in the 17th Canadian Parliament.