Gary James Cahill is an English professional footballer who plays as a centre-back for Premier League club Chelsea and is the vice-captain of the England national team.

Cahill began his career playing for the AFC Dronfield youth set-system in Derbyshire. In 2000, he joined the Aston Villa Academy and continued his development. In 2004, he joined Burnley on a season-long loan, where he performed well before returning to make his Aston Villa debut. Later, he signed for hometown club Sheffield United on a three-month loan deal. On 30 January 2008, he signed for Bolton Wanderers for approximately £5 million. Cahill performed well for Bolton through the years, cementing a place in the first team and becoming vice-captain. He made 130 league appearances and scored 13 league goals for Bolton. In January 2012, Cahill signed for Chelsea for approximately £7 million. Cahill won the UEFA Champions League and the FA Cup in his debut season at Chelsea, and went on to win the UEFA Europa League, League Cup and Premier League.

Cahill is an English international with over 40 caps and represented the nation at the 2014 FIFA World Cup. He was eligible to play for either England or the Republic of Ireland, but chose to play for England. In June 2009, Cahill was called up to the England squad for the match against Kazakhstan. However, he only made his debut on 3 September 2010, coming on as a substitute against Bulgaria. On 29 March 2011, Cahill made his first start for the national team in the friendly against Ghana. He scored his first international goal against Bulgaria in a UEFA Euro 2012 qualifier.