Henry Greathead Rex Mason was a New Zealand politician. He served as Attorney General, Minister of Justice, Minister of Education, and Minister of Native Affairs, and had a significant influence on the direction of the Labour Party. The longest-serving Member of Parliament in New Zealand history, Mason served in Parliament continuously from 1926 to 1966. He is also the only person to serve as an Member of the New Zealand Parliament for over 40 years.

The Attorney-General is a political and legal officer in New Zealand. The Attorney-General is simultaneously a ministerial position and the chief law officer of the Crown, and has responsibility for supervising New Zealand law and advising the government on legal matters. The Attorney-General serves both a political and apolitical function. The current Attorney-General is Judith Collins.