Saint Thomas Aquinas is a Catholic secondary school educating grades 9–12, located in Tottenham, Ontario, Canada.

It is part of the Simcoe Muskoka Catholic District School Board.

The school participates in county sporting events under the name of the "Stingers".

The school was founded in 1969 and offers a range of classes to its students.

The high school serves students from New Tecumseth, Adjala–Tosorontio, Southern Essa Township and a portion of Bradford West Gwillimbury.