Willie Manu (born 20 March 1980) is an Australian professional rugby league footballer for the Sydney Roosters of the National Rugby League. A Tonga national representative second-row forward, he previously played in the National Rugby League for Australian clubs the Wests Tigers, South Sydney Rabbitohs and St. George Illawarra Dragons. Manu moved to England and played for Super League clubs Castleford Tigers then Hull FC before joining St Helens, with whom he won the 2014 Super League championship.
In August 2008, Willie Manu was named in the Tonga training squad for the 2008 Rugby League World Cup, and in October 2008 he was named in the final 24-man Tonga squad. He played for Tonga in 2009 in a Test match against the New Zealand Kiwis.
St. Helens reached the 2014 Super League Grand Final and Manu was selected to play from the interchange bench in their 14-6 victory over Wigan Warriors.