The Leader of the Opposition in Ontario is usually leader of the largest party in the Ontario legislature which is not the government. The current official opposition is formed by the Ontario Progressive Conservative Party however, and John Tory is the current Leader of the Opposition.

Ontario's first Leader of the Opposition was Edward Blake of the Ontario Liberal Party who held the position from 1869 until 1871 when he became Premier of Ontario (Archibald McKellar had previously led the Liberal Party in the legislature for two years, but was not formally recognized as opposition leader).

See also

• List of Leaders of the Opposition in Ontario