Susan "Sue" Lines (born 15 December 1953) is an Australian trade union official and Labor Party member of the Australian Senate for Western Australia.
Lines was born in Perth, Western Australia, and educated at Armadale Senior High School and Murdoch University. She has been a member of the United Voice trade union since 1987, and was the Sydney-based assistant national secretary of the union at the time of her nomination for appointment to the Senate.
On 15 May 2013, a joint sitting of the Parliament of Western Australia appointed Lines to fill the casual vacancy in the Senate caused by the resignation of Senator Chris Evans.
Lines became Deputy President of the Australian Senate on 30 September 2016.
She is a member of the Australian Labor Party National Executive.