The 512 St. Clair is an east–west streetcar route in Toronto, Ontario, Canada, operated by the Toronto Transit Commission (TTC). It operates on St. Clair Avenue between St. Clair station on the Line 1 Yonge–University subway and Gunns Road, just west of Keele Street.

The Toronto streetcar system is a network of eleven streetcar routes in Toronto, Ontario, Canada, operated by the Toronto Transit Commission (TTC). It is the third busiest light-rail system in North America. The network is concentrated primarily in Downtown Toronto and in proximity to the city's waterfront. Much of the streetcar route network dates from the 19th century. Three streetcar routes operate in their own right-of-way, one in a partial right-of-way, and six operate on street trackage shared with vehicular traffic with streetcars stopping on demand at frequent stops like buses. Since 2019, the network has used low-floor streetcars, making it fully accessible.