Viliami 'Billy' Vunipola is a professional rugby union player who plays at number 8 for Saracens in the English Premiership and for the England national team. Born in Australia to Tongan parents, he qualified for England through residency. He made his England debut in 2013 and has since won 36 caps.
While at Harrow School, he joined the Wasps Academy. He made his senior team debut in 2011–12 season and played 30 matches over two seasons before leaving at the end of the 2012–2013 season. Vunipola signed a contract in January 2013 to move to Saracens at the end of the 2012–13 Aviva Premiership.
After representing England at U18 and U20 level, Vunipola was called up to the England Saxons Squad in January 2013. He trained with the England Squad during the 2013 Six Nations Championship and made his senior England debut during the England tour of Argentina in the test against Argentina in Salta in June 2013, coming off the bench to score a try in England's 32–3 win. Earlier in the tour he played in an uncapped match against a Consur XV, and scored a hat-trick of tries in six minutes.
England Head Coach Stuart Lancaster selected Vunipola in his squad for the Autumn Internationals. Vunipola was named man of the match for the Scotland–England, England-Ireland and France-England matches in the 2016 Six Nations Championship.
In April 2017, Vunipola was selected as the one of the 41 British and Irish Lions to tour New Zealand in the summer alongside with his brother Mako Vunipola. However due to an ongoing shoulder injury, he withdrew from the squad on 21 May 2017 and was replaced by England back-row teammate James Haskell.