Libertarian Party: A third party in US politics that emphasizes individual liberty, non-interventionism, laissez-faire capitalism, and shrinking the size and scope of government.
Green Party: Another third party in US politics that focuses on green politics, including environmentalism, non-violence, social justice and grassroots democracy.
Populist Party: A historical third party in US politics from late 19th century which advocated for various reforms like a graduated income tax and an eight-hour work day.