The 34-year-old, a two-time Rugby World Cup winner with New Zealand, has switched codes again having signed a contract reportedly worth 9million Canadian dollars that will make him the highest-paid rugby league player in the world.
Williams, who featured for the All Blacks in their run to the World Cup semi-finals last month, began his professional career in the NRL with Canterbury Bulldogs.
After winning a Premiership with the Bulldogs, he switched to union to play for Top 14 club Toulon but returned to the NRL in 2013, winning a second title with Sydney Roosters.
