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.