Joseph McKenna was an American politician who served in all three branches of the U.S. federal government as a member of the U.S. House of Representatives, as U.S. Attorney General and as an Associate Justice of the Supreme Court. He is one of seventeen members of the House of Representatives who subsequently served on the Supreme Court.

An associate justice of the Supreme Court of the United States is a justice of the Supreme Court of the United States, other than the chief justice of the United States. The number of associate justices is eight, as set by the Judiciary Act of 1869.