S
- Sable
- Sabourins Crossing
- Saganaga Lake
- Saginaw
- Sahanatien
- Saintfield
- Salem, Bruce County
- Salem, Dufferin County
- Salem, Durham Regional Municipality
- Salem, Frontenac County
- Salem, Northumberland County
- Salem, Wellington County
- Salford
- Salisbury
- Salmon Point
- Salmontville
- Saltford
- Sam Lake
- Sandford
- Sand Banks
- Sand Bay Corner
- Sandcastle Beach
- Sandfield
- Sandringham
- Sandy Hill
- Sandy Lake
- Sans Souci
- Sarepta
- Sarnia
- Sauble Beach
- Sauble Beach North
- Sauble Beach South
- Sauble Falls
- Saugeen
- Sault Ste. Marie
- Savant Lake
- Schipaville
- Scone
- Scotch Block
- Scotch Bush, Hastings County, Ontario; Scotch Bush, Renfrew County, Ontario
- Scotch Corners
- Scotia
- Scotland
- Scugog
- Scugog Centre
- Schomberg
- Schreiber
- Sebright
- Seagrave
- Seaforth
- Seeley
- Seeleys Bay
- Seguin
- Selby
- Selkirk
- Selton
- Selwyn
- Senecal
- Seouls Corner
- Sesekinika
- Seven Mile Narrows
- Severn Bridge
- Severn Falls
- Shady Nook
- Shakespeare
- Shallow Lake
- Shamrock
- Shannon Hall
- Shannonville
- Shanty Bay
- Sharbot Lake
- Sharon
- Shebandowan
- Shebeshekong
- Shedden
- Sheffield
- Shelburne
- Sherwood
- Sherwood Springs
- Shetland
- Shillington
- Shiloh
- Shouldice
- Shrigley
- Siberia
- Silver Creek
- Silver Dollar
- Silver Hill
- Simcoe
- Simpson Corners
- Singhampton
- Sioux Lookout
- Sioux Narrows
- Skerryvore
- Skipness
- Slate Falls
- Sleeman
- Smithdale
- Smiths Falls
- Smithville
- Smooth Rock Falls
- Snelgrove
- Snowball
- Snow Road Station
- Snug Harbour
- Snug Haven
- Sodom
- Sonya
- Soperton
- South Augusta
- South Beach
- South Branch
- Southcott Pines
- South Crosby
- South Dummer
- South March
- South Middleton
- South Monaghan
- South River
- South Wilberforce
- Southampton
- Sowerby
- Spanish
- Sparkle City
- Sparta
- Speedside
- Spence
- Speyside
- Spicer
- Spier
- Spring Bay
- Springbrook
- Springfield
- Springford
- Springhill
- Springmount
- Springvale
- Spring Valley
- Springville
- Springwater
- Squire
- Squirrel Town
- St. Agatha
- St. Albert
- St. Andrews
- St. Anns
- St. Augustine
- St. Bernardin
- St. Catharines
- St. Charles
- St. Clair Beach
- St. Clements
- St. Cloud
- St. Columban
- St. David's, Niagara Regional Municipality
- St. Davids, Prescott and Russell United Counties
- St. Elmo, Muskoka District Municipality
- St. Elmo, Stormont, Dundas and Glengarry United Counties
- St. Eugene
- St. Felix
- St. George
- St. Helens
- St. Isidore
- St. Jacobs
- St. Joachim
- St. Johns, Brant County
- St. Johns, Niagara Regional Municipality
- St. Joseph
- St. Joseph, Huron County
- St. Joseph Island
- St. Marys
- St. Ola
- St. Williams
- St. Pascal Baylon
- St. Pauls
- St. Pauls Station
- St. Raphaels
- St. Thomas
- St. Williams
- Stamford
- Stanleydale
- Stanton
- Stayner
- Ste-Anne-de-Prescott
- Stella
- Ste-Rose-de-Prescott
- Stevensville
- Stewarttown
- Stinson
- Stirling
- Stirling Falls
- Stittsville
- Stonebrook
- Stonecliffe
- Stonehart
- Stones Corners
- Stoney Creek
- Stoney Point
- Stories
- Storms Corners
- Stouffville
- Strange
- Stratford
- Strathavon
- Strathmore
- Strathroy-Caradoc
- Streetsville
- Stroud
- Sturgeon Falls
- Sturgeon Point
- Sudbury
- Sulphide
- Summerhill
- Summers Corners
- Sunderland
- Sundridge
- Sunfish Lake
- Sunnidale, Lambton County, Ontario; Sunnidale, Simcoe County, Ontario; Sunnidale Corners, Ontario
- Sunnidale Corners
- Sunny Slope
- Sunrise Beach
- Sunset Bay Estates
- Sunset Beach, several
- Sunset Corners
- Sutton
- Swan Crossing
- Swansea
- Swastika
- Sweets Corners, Haldimand County, Ontario; Sweets Corners, Leeds and Grenville United Counties, Ontario
- Swindon
- Swinton Park
- Switzerville
- Sydenham, Frontenac County
- Sydenham, Grey County
- Sylvan Valley
Read more about this topic: List Of Communities In Ontario