Nathaniel McLenaghan (November 11, 1841 – September 26, 1912) was an Ontario merchant and political figure. He represented Lanark South in the Legislative Assembly of Ontario from 1890 to 1893 as a Conservative member.He was born in Drummond Township, Canada West in 1841, the son of Irish immigrants, and educated in Perth. He taught school for several years before becoming involved in exporting cattle. McLenaghan served on the town council for Perth.