David Stephen "Dai" Llewellyn (born 29 September 1970) is a former Wales international rugby union player. He played his club rugby for Newport and Neath and was part of the Wales squad for the 1999 World Cup where he scored a try.
Llewellyn won four caps for Wales between 1998 and 1999. He featured a further twelve times on the bench for his country. Llewellyn played in the last ever Five Nations tournament and made one appearance in the 1999 Rugby World Cup as a replacement against Japan.
He now works as a personal trainer at Fitness First Cardiff East.