Jason Paul Cayless[3] (born 15 January 1980) is a former New Zealand international rugby league footballer who played as a prop in the 2000s and 2010s.

The following year Cayless moved to the Sydney Roosters and played for them at prop forward in their 2002 NRL Grand Final win over the New Zealand Warriors.

Having won the 2002 NRL Premiership, the Roosters traveled to England to play the 2003 World Club Challenge against Super League champions, St Helens.

Cayless played for St Helens as a prop forward in their 2006 Challenge Cup Final victory against the Huddersfield Giants.

As 2006 Super League champions, St Helens faced 2006 NRL Premiers the Brisbane Broncos in the 2007 World Club Challenge.