Sian Williams (born 23 October 1990) is a Welsh rugby union player who plays in the back row for Worcester/Newport Gwent Dragons and the Wales women's national rugby union team.

As of 2016[update], her official Wales Rugby Union biography states that she is 1.62 metres (5.3 ft) tall, and weighs 74 kilograms (11.7 st).

[4] Outside of rugby, she was a logistics mover with the rank of Senior Aircraftwoman for the Royal Air Force.

[4] That was until 10 February 2016,[5] when it was announced that Williams had signed a professional rugby contract, having been granted elite athlete status by the RAF meaning that she would continue to be employed by the forces while being able to train full-time.

Following the signing of the professional contract, Williams was re-located to RAF St Athan, where she could train with Wales head coach Rhys Edwards on a full-time basis for the next two years.