The 505 Dundas is a streetcar line run by the Toronto Transit Commission in Toronto, Ontario, Canada. It runs on two parallel pairs of tracks laid in the same lanes used by car traffic. Two 600 volt direct current overhead cables supply the electrical power to the streetcars. The route was previous un-numbered and was referred to as the Dundas.
The route starts at Dundas West subway station on the Bloor-Danforth line and goes south along Dundas Street West. The street curves southeast and passes Howard Park. Here it briefly merges with the 506 Carlton line as it passes over a bridge for the main Canadian National Railways line that runs down to Union Station. To the east of the bridge past Lansdowne Avenue it continues on its own again. At Ossington Avenue, it turns eastward and passes through Toronto's original Chinatown and goes by the Art Gallery of Ontario before meeting up with the St. Patrick subway station at University Avenue.
Shortly after that it crosses Yonge Street and passes by the Dundas subway station. It continues east towards Broadview Avenue where it turns north and merges with the 504 King streetcar line. Both streetcars end their journey at Broadview subway station on the Bloor-Danforth line.
The route operates seven days a week from early morning to after midnight. During weekday rush hours, day time and early evenings, average service frequency is 5–7 minutes. Saturday daytime services have an average frequency of 5–7 minutes with Sunday daytime service frequency averaging 6–8 minutes.