John Leys was an Ontario lawyer and political figure.
He was born in Pickering, Ontario County, Upper Canada in 1834, the son of Francis Leys, a Scottish immigrant.
He represented Toronto in the Legislative Assembly of Ontario from 1886 to 1890 as a Liberal member. He was educated at the Toronto Academy. Leys studied law with Angus Morrison, was called to the bar in 1860 and set up practice in Toronto.
He served as solicitor for the Toronto and Nipissing Railway and was involved in the development of the Narrow Gauge Railway.
He ran unsuccessfully in Toronto East in 1879 and 1882 before his election to the provincial assembly in 1886.