Samuel Johnson Haynes (22 March 1852 – 3 February 1932) was an Australian barrister and politician who served as a member of the Legislative Council of Western Australia from 1894 to 1910, representing South-East Province.
His parents left for Australia when he was a small child, settling in Port Fairy, Victoria.
Haynes was sent to grammar school in England, but returned to Australia to study law.
In 1888, Haynes moved to Albany, Western Australia, where he established his own law firm.
He eventually went into partnership with Robert Thomson Robinson, a future Attorney-General of Western Australia.