Glenforest Secondary School (GFSS) is a public secondary educational institution located in Mississauga, Ontario, Canada. Established in 1969, Glenforest Secondary School is a member of the Peel District School Board and offers an International Baccalaureate program. The school mascot is the mythological creature, the gryphon.
In 2014, GFSS drama students performed an adaptation of Don Quixote. The school's indoor swimming pool, which it shared with the city, was demolished in 2024.
Teacher Rachel Luke received the prime minister's award for teaching excellence in science, technology, engineering and mathematics (STEM).