S
- (Cochrane District) Shillington
- (Northumberland County) Shiloh
- (Wellington County) Shiloh
- (Durham) Shirley
- (Ottawa) Shirleys Bay
- (Grey County) Shouldice
- (Oxford County) Showers Corners
- (Dufferin County) Shrigley
- (Renfrew County) Siberia
- (Wellington County) Signet
- (Durham) Siloam
- (Regional Municipality of Niagara) Silverdale
- (Renfrew County) Silver Lake
- (Frontenac County) Simcoe Island
- (Simcoe County) Simcoe Lodge
- (Wellington County) Simpson Corners
- (Lanark County) Sinclair Shore
- (Hastings County) Sine
- (Kenora District) Sioux Lookout
- (Kenora District) Sioux Narrows
- (Parry Sound District) Skerryvore
- (Ottawa) Skyline
- (Renfrew County) Slabtown
- (Bruce County) Slade
- (Lennox and Addington County) Slate Falls
- (Thunder Bay District) Slate River Valley
- (Simcoe County) Smithdale
- (Nipissing District) Smith's Landing
- (Regional Municipality of Niagara) Smithville
- (York) Snowball