Theo James Walcott (born 16 March 1989) is an English footballer who plays for Arsenal and the England national team as a striker.

Walcott was born in Stanmore, England, but grew up near Newbury, where he played for A.F.C. Newbury and went to The Downs School secondary school. Walcott scored more than 100 goals in his one and only season for Newbury, before leaving there for Swindon Town. He only spent six months there before leaving for Southampton after he rejected a chance to join Chelsea. Nike agreed to a sponsorship deal with Walcott when he was fourteen years old.

In the 2004–05 season, he starred in the Southampton youth side that reached the final of the FA Youth Cup against Ipswich Town. In addition, he became the youngest person to play in the Southampton reserve team at 15 years and 175 days, when he came off the bench against Watford in September 2004. However, he did not play in the Premier League, as Southampton were relegated to the Championship at the end of the 2004–05 season.

Before the start of the 2005–06 season, Walcott linked up with the first team's tour of Scotland, just two weeks after leaving school. The striker then went on to become the youngest-ever player to play for the Southampton first team at 16 years and 143 days, after coming on as a substitute in Southampton's 0–0 draw at home to Wolverhampton Wanderers in the Football League Championship.

Walcott made his full first team debut away to Leeds United on 18 October 2005, scoring his first senior goal in the same game. He scored again away at Millwall four days later, and yet again in his full home debut against Stoke City the following Saturday. His rapid rise to fame also led him to be named amongst the top three finalists for the prestigious BBC Young Sports Personality of the Year award on 11 December 2005.

Walcott transferred to Arsenal on 20 January 2006, for a fee of £5 million, rising to £12 million depending on appearances for club and country. The original fee was payable by instalments – £5 million down, £5 million based on club appearances and £2 million based on England appearances – but was revised to a total of £9.1 million by a compromise settlement agreed on 31 March 2008. He signed an initial pre-contract agreement to sign a professional contract on his 17th birthday on 16 March 2006, and was given the number 32 shirt in the process.

Following his surprise and controversial selection in the England squad for the World Cup 2006, he made his Premier League debut on 19 August 2006, the first day of the 2006–07 season, coming on as a substitute against Aston Villa and setting up a goal for Gilberto Silva.

A UEFA Champions League debut came in the second leg of Arsenal's third qualifying round match against Dinamo Zagreb, where Walcott became the youngest ever Arsenal player to appear in European competition, a record previously held by Cesc Fàbregas, and since beaten by Jack Wilshere. Within minutes of coming on he received his first yellow card in Arsenal colours for taking a shot several seconds after the referee had already blown for offside. During stoppage time his cross beat the Dinamo defence and Mathieu Flamini scored, giving Walcott a record of two assists in two substitute appearances. His first start came in a home league game against Watford on 14 October 2006. Walcott's exploits with Arsenal and with the England team earned him the BBC Young Sports Personality of the Year award at the end of 2006.

Walcott's first goal for Arsenal came in the 2007 League Cup Final against Chelsea at the Millennium Stadium, Cardiff, on 25 February 2007, but his eleventh minute strike was overshadowed by events later on in the match as Didier Drogba scored twice to give Chelsea a 2–1 victory and three players were dismissed following a mass brawl.

Walcott's first home goals were scored in a Champions League match against Slavia Prague, which Arsenal won 7–0, as well as setting up a goal for Fàbregas. Walcott scored his first two Premier league goals in a 2–2 draw against Birmingham City at St. Andrews on 23 February 2008. He finished the 2007–08 season with seven goals from all competitions. In the Champions League quarterfinal against Liverpool on 8 April, Walcott made a run from inside his own half down the length of the pitch, beating the Liverpool back four to set up Emmanuel Adebayor's last minute equalizer.