Archibald McKellar (3 February 1816 – 11 February 1894) was briefly leader of Canada's Ontario Liberal Party from 1867 to 1868 and, unofficially, the first Leader of the Opposition in Ontario's new provincial legislature (though he was not officially recognised as such) and went on to serve as Commissioner of Public Works in Ontario Premier Oliver Mowat's first government.He was born in Inveraray, Scotland in 1816 and came to Upper Canada with his parents in 1817.