Gareth Williams (born 5 September 1981) is a Welsh former rugby union player who played as a flanker.
Born in Aberystwyth but raised in the village of Tumble, Carmarthenshire, he played club rugby for Llanelli, Carmarthen Quins and Llandovery, and was also part of the Llanelli Scarlets regional side for the first season of regional rugby in Wales in 2002–03.
He made five appearances in the 2001–02 season, and scored another try after coming off the bench in a win over Newbridge.
In 2003–04, he again played for both Llanelli and Quins, but was also part of the squad for the Scarlets regional side and made three appearances in the opening months of the season before a run of five starts in February and March 2004, in the absence of Ian Boobyer due to injury.
His last game in senior rugby came in November 2010, in a loss to Neath.