Ashton Charles Agar is an Australian cricketer who plays all forms of the game at international level. Agar plays domestically for Western Australia and the Perth Scorchers. A left-handed spin bowler, he played two Test matches for the Australian national side during the 2013 Ashes series and 5 Test matches in his career. Agar was also a member of the Australian team that won the 2021 T20 World Cup in Dubai and Oman.

He represented Victoria at both under-17 and under-19 level. After good form at the 2010–11 National Under-17 Championships, where he took 16 wickets at an average of 11.75 bowling left-arm orthodox spin, he was selected to play for the Australian under-19s for a series against the West Indies under-19s in the United Arab Emirates. Making his debut at the age of 17, Agar went on to play one under-19 Test and ten under-19 One Day International (ODI) matches for Australia. At the 2012 Under-19 World Cup, he was named in the squad as Australia's second spinner behind Ashton Turner, but did not play a match at the tournament.

Having failed to gain selection at senior level for Victoria, Agar moved to Western Australia for the 2012–13 season, where he was awarded a contract with the Western Australian Cricket Association (WACA). He made his first-class debut for Western Australia in a Sheffield Shield match against New South Wales in January 2013, replacing the injured Michael Beer as the side's spinner. Agar made his List A debut for Western Australia in the limited-overs Ryobi One-Day Cup in late January, and took five wickets from his two matches, with his best figures 3/51 against Queensland.

Agar made his Sheffield Shield debut in January 2013. The following month, he was called up for Australia's 2012–13 tour of India, where he played a single tour match. Agar toured England and Ireland with Australia A in mid-2013, performing well in the English conditions. Although originally not selected in the touring squad, he made his Test debut for Australia in the first Test of the 2013 Ashes series. Coming in with the score on 117/9, Agar scored 98 runs batting eleventh in Australia's first innings, Agar broke several Test records on debut, including the highest score by a number-11 batsman and the highest partnership for the tenth wicket (with Phillip Hughes – since broken). However, after poor bowling, he was dropped from the team after the second Test of the series.

In February 2013, Agar was a late inclusion in the Australian squad for the 2012–13 tour of India, and played a single match on tour, taking 3/107 against India A. He finished the Sheffield Shield season with 19 wickets from five matches, including a five-wicket haul, 5/65, taken against South Australia in early March.

Agar made his Twenty20 debut for the Perth Scorchers in the 2013 Champions League Twenty20 in India. Agar played only a single match during the 2013–14 Big Bash League season, but the following season featured in eight of the Scorchers' ten matches. He took eight wickets at an average of 24.25, ranked thirteenth in the competition and fourth for the Scorchers, behind Jason Behrendorff, Yasir Arafat, and Andrew Tye.

As for his international career, Agar was selected to tour England, Scotland, and Ireland with Australia A in June 2013. Following his good form for Australia A, Agar was named to make his Test debut in the first Test of the series (played at Trent Bridge, Nottingham), replacing Lyon in the side from the previous tour. Aged 19 years and 269 days, he became the twelfth-youngest Australian Test player, as well as the youngest Australian since Archie Jackson (during the 1928–29 series) to make his Test debut in the Ashes. On debut, he scored 98 runs from 101 balls batting eleventh in Australia's first innings, breaking several Test records, including first player to ever score a half-century as a number eleven batsman on debut, highest score by a number eleven batsman, and, with Phillip Hughes, highest partnership (163 runs) for the tenth wicket. Agar played in the first two Tests of the series, and despite his debut batting performance, had very limited success with the ball, taking 0/24, 2/82, 0/44 and 0/98 for a bowling average of 124. He was subsequently dropped from the team for the third and fourth Tests, and returned home due to illness ahead of the final Test.

He made his One Day International debut against England on 8 September 2015. He made his Twenty20 International debut for Australia against South Africa on 6 March 2016.

In 2017, Agar was recalled to the Australian test side for their tour of Bangladesh, and in the first test match, took 5 wickets in total, as well as scoring an impressive 41 not out in Australia's first innings. Despite his efforts, Australia lost to Bangladesh for the first time in Test cricket.

In April 2018, he was awarded a national contract by Cricket Australia for the 2018–19 season.

On 21 February 2020, in the first T20I match against South Africa, Agar became the second bowler for Australia, and 13th overall, to take a hat-trick in a T20I match. He finished the match with figures of 5/24 from his four overs, his first five-wicket haul in a T20I match.

On 3 March 2021, during the series against New Zealand, Agar took the best figures for a bowler for Australia, and the fifth-best figures overall in T20Is, with 6/30 from his four overs. In August 2021, Agar was named in Australia's squad for the 2021 ICC Men's T20 World Cup.

In March 2022, Agar was added to the Australian test, ODI, and T20 squad ahead of its tour of Pakistan. However, Agar was withdrawn from the T20 squad after testing positive for coronavirus.