George Frederick Marter (6 June 1840 – 10 May 1907) was a politician in the Canadian province of Ontario.
Marter and Patrick Brown are the only permanent Ontario Conservative leaders who did not lead the party into an election.
In 1894, Marter became Conservative leader following William Ralph Meredith's acceptance of the position of Chief Justice of the Common Pleas.
The Conservative Party he led was aligned with the Protestant Protective Association in the legislature, and was divided by religious conflict and narrow bigotry.
Following his political career Marter became an insurance agent/manager of the London and Lancashire Insurance Company of Toronto and later co-founder of Marter Hall Company Limited with his son.