Mike Schreiner is a Canadian politician who has served as the leader of the Green Party of Ontario since 2009. Schreiner sits as a member of Provincial Parliament (MPP), representing Guelph; his 2018 election made him the first Green Party member elected to the Legislative Assembly of Ontario.

The Legislative Assembly of Ontario is the legislative chamber of the Canadian province of Ontario. Its elected members are known as Members of Provincial Parliament (MPPs). Bills passed by the Legislative Assembly are given royal assent by the lieutenant governor of Ontario to become law. Together, the Legislative Assembly and Lieutenant Governor make up the unicameral Legislature of Ontario or Parliament of Ontario. The assembly meets at the Ontario Legislative Building at Queen's Park in the provincial capital of Toronto.