John Leslie Mackie (25 August 1917–12 December 1981) was an Australian philosopher.
He made significant contributions to the philosophy of religion, metaphysics, and the philosophy of language, and is perhaps best known for his views on meta-ethics, especially his defence of moral scepticism.
He authored six books.
His most widely known, Ethics: Inventing Right and Wrong (1977), opens by boldly stating that "There are no objective values." It goes on to argue that because of this ethics must be invented, rather than discovered.