Stevie Ward has ended his playing career at just 27 as a result of continued symptoms following two concussions last year.
St Helens retained their Grand Final trophy in a frantic finish against rivals Wigan Warriors.
Catalans Dragons had two men sent to the sin bin and conceded 48 unanswered points in a humiliating defeat to St Helens.
Sean O'Loughlin will end his career in next week's Super League Grand Final after Wigan crushed Hull on Thursday.
Former Leeds Rhinos star Ryan Hall is back in Super League, signing a two-year deal with Hull KR.
Lionel Messi's future remains unclear, and Manchester City are said to be making plans to move for the Barcelona captain.
Catalans Dragons set up a Super League play-off semi-final against St Helens with victory over Leeds Rhinos on Friday.
Sean O'Loughlin will call time on a 19-year career with the Wigan Warriors at the end of the Super League season.
Jackson Hastings inspired Wigan Warriors to a victory over Huddersfield Giants that crowned his side as League Leaders' Shield winners.
Following the decision not to readmit Toronto Wolfpack, the Super League has voted to go back to a 12-team competition next season.