Leaside is a neighbourhood in Toronto, Ontario, Canada. The area takes its name from William Lea and the Lea family, who settled there in the early years of the nineteenth century. The area first developed as farmland along with Toronto through the nineteenth century. It was incorporated as a town in 1913. In 1967 it was amalgamated with the township of East York to form the borough of East York. In 1998 it became part of the city of Toronto.
The general area of Toronto had been inhabited by various Natives at least as early as 3000 BCE, when the Laurentian peoples moved south into the area just east of Toronto. The first European known to travel to the area was Étienne Brûle, who passed through the area in the early part of the seventeenth century. Surveying and settlement by Europeans began in earnest in the 1780s, with the influx of Loyalists fleeing the American Revolution.