Tina Michelle O'Brien is an English actress. She is best known for her portrayal of Sarah Platt in the long-running ITV soap opera Coronation Street. She also appeared in the BBC One drama series Waterloo Road (2010–2011).

Sarah-Louise Barlow is a fictional character from the British ITV soap opera Coronation Street. She was born on-screen during the episode broadcast on 2 February 1987. She was played by Leah King in 1987 and by Lynsay King from 1987 until 8 October 1999 when King opted to leave to focus on her education. Tina O'Brien took over the role on 31 October 1999; she opted to leave in 2007 and made her final on-screen appearance on 30 December 2007, although she made some brief voice-over appearances the following month. A number of false rumours about O'Brien returning to the role surfaced during her absence from the serial. In October 2014, it was announced that O'Brien would reprise the role, with Sarah returning on 30 March 2015.