Ian Michael Chappell is a former cricketer who played for South Australia and Australia. Known as "Chappelli", he is considered as one of the greatest captains the game has seen. He captained Australia between 1971 and 1975 before taking a central role in the breakaway World Series Cricket organisation. Born into a cricketing family—his grandfather and brother also captained Australia. Ian Chappell fashioned an Australian team in his own image; aggressive, resourceful and insouciant. A dauntless batsman partial to the hook and pull, he inherited the post of captain from Bill Lawry with the team at a low ebb, but others fed off his unhesitating self-belief and conviction that team goals were paramount, and in turn, he never lost a series.

The first of four sons born in Unley, near Adelaide, Chappell was steeped in the game from an early age. His father was a noted Adelaide grade cricketer who put a bat in his hands as soon as he could walk, and his maternal grandfather was famous all-round sportsman Vic Richardson, who captained Australia at the end of a nineteen-Test career. Chappell was given weekly batting lessons from the age of five, as were younger brothers Greg and Trevor, who both also went on to play for Australia. At the age of 18, his form in grade cricket for Glenelg led to his first-class debut for South Australia (SA) against Tasmania in early 1962.

The aggressive style of Sobers and of South Australia captain Les Favell heavily influenced Chappell during his formative years in senior cricket. In 1962/63, Chappell made his initial first-class century against a New South Wales team led by Australian captain Richie Benaud, who was bemused by the young batsman's habit of gritting his teeth as he faced up; to Benaud, it looked as if he was grinning. Chappell spent the northern summer of 1963 as a professional in England's Lancashire League with Ramsbottom. In 1963/64, Chappell batted at number three for SA for the first time, in a match against Queensland at Brisbane, and scored 205 not out. He was the youngest member of the SA team that won the Sheffield Shield that season. A century against Victoria early the following season resulted in Chappell's selection for a one-off Test against Pakistan at Melbourne in December 1964.

He retained his place for the following Test and for the tour of South Africa in summer 1966/67. Playing in a side defeated 1–3, Chappell struggled to make an impression. His highest score in ten Test innings was 49, while his five wickets cost 59 runs each, but he rode his luck in the 2nd Test to score 151 – his innings contained five chances that the Indians failed to take. In England, Chappell rewarded the faith of the selectors by scoring the most first-class runs on the tour (1,261 runs, including 202 not out against Warwickshire). His top score was 81 in the fourth Test at Leeds. Wisden lauded his play off the back foot and judged him the most difficult Australian batsman to dismiss.

A string of big scores and a record number of catches during the 1968/69 season earned Chappell the Australian Cricketer of the Year award. Against the touring West Indies, Chappell hit 188 not out, 123, 117, 180 and 165 before the New Year. Two of these centuries came in the Test series, when Chappell's average for 548 runs was 68.50. Chappell was elevated to number three in the batting order and became a less-frequent bowler; he was also appointed vice-captain of the team.

Following up with a successful tour of India in late 1969, Chappell demonstrated his fluency against spin bowling by compiling Test innings of 138 at Delhi and 99 at Kolkata. His ability against both fast and slow bowling earned high praise, including from his captain Bill Lawry. On this tour, Chappell clashed with cricket administrators over pay and conditions for the first time. The South African authorities requested that an extra Test be added to the fixture and the Australian Board of Control consented. Eventually the match was cancelled after Chappell and his supporters refused to back down.

Chappell became South Australian captain when the long-serving Les Favell retired at the start of the 1970/1971 season. His younger brother Greg made his debut in the second Test of the summer against Ray Illingworth's England. Temporarily promoted to open the batting, Chappell failed in the fourth Test as Australia lost. In the fifth Test at Melbourne, he returned to number three and started nervously. Dropped on 0 and 14, Chappell found form and went on to post his maiden Ashes century (111 from 212 balls), which he followed with scores of 28 and 104 in the sixth Test.

The washed-out Test resulted in a late change to the schedule and an unprecedented seventh Test was played at Sydney in February 1971. Trailing 0–1 in the series, Australia could retain The Ashes by winning this game. Chappell responded with an attacking performance as captain, he won the toss, put England in and dismissed them for 184, and Australia led the first innings by 80 runs, but set 223 to win they folded for 160 and lost The Ashes after holding them for 12 years. Chappell gained some consolation at the end of a dramatic summer when he led SA to the Sheffield Shield, the team's first win for seven years.

Chappell's battles against the short-pitched bowling of Snow during the season compelled him to reappraise his game. Following a conversation with Sir Donald Bradman, he decided to reinstate the hook shot and spent the winter months practising the stroke by hitting baseballs thrown by his brother Greg. Greg Chappell emerged as a prolific batsman during the next Ashes series, batting one place below his brother in the order. The siblings shared several crucial partnerships, most notably 201 at the Oval in the last Test when they became the first brothers to score centuries in the same Test innings. Australia won the game, an effort that Chappell later cited as the turning point in the team's performances.

In 1972/73, Australia had resounding victories against Pakistan (at home) and the West Indies (away). Chappell's leadership qualities stood out in a number of tight situations. He hit his highest Test score of 196 (from 243 balls) in the first Test against Pakistan at Adelaide. On indifferent pitches in the Caribbean, Chappell was the highest-scoring batsman of the Test series with 542 runs (at 77.4 average). He hit 209 in a tour match against Barbados, two Test centuries and a "glorious" 97 on a poor pitch at Trinidad in the third Test, batting with an injured ankle. This set up a dramatic last day when the West Indies needed just 66 runs to win with six wickets in hand at lunch. The home team collapsed against an inspired Australian bowling attack supported by Chappell's aggressive field-placements.

Australia played six Tests against New Zealand on both sides of the Tasman in 1973/74. Chappell led his team to a 2–0 victory in the three Tests played in Australia. During the third Test at Adelaide, he equalled the world record of six catches in a Test match by a fielder, which was beaten by his brother Greg the following season. In the drawn first Test at Wellington, the Chappells became the first brothers to each score a century in both innings of a Test match. The Australians lost to the Kiwis for the first time ever in the second Test at Christchurch, when Chappell was involved in a verbal confrontation with the leading New Zealand batsman, Glenn Turner. The Australians then played an ill-tempered tour match at Dunedin that didn't enhance the reputation of Chappell or his team with their ‘sledging’, before winning the final Test at Auckland. On this tour, the behaviour of the team was questioned with some journalists labelling them "ugly Australians".

The highlight of Chappell's career was Australia's 4–1 win over England in 1974/75 that reclaimed The Ashes. Strengthened by the new fast bowling partnership of Dennis Lillee and Jeff Thomson, the Australians played aggressive cricket and received criticism for the amount of short-pitched bowling they employed. Chappell scored 90 on an "unreliable" pitch on the first day of the opening Test at Brisbane. The Test matches attracted big crowds and record gate takings, enabling Chappell to negotiate a bonus for the players from the Australian Cricket Board (ACB).

Within months, Chappell was back in England leading Australia in the inaugural World Cup. His dislike of the defensive nature of limited-over cricket led to the Australians placing a full slips cordon for the new ball and employing Test-match style tactics in the tournament. Despite the apparent unsuitability of this approach, Chappell guided the team to the final where they lost a memorable match to the West Indies. The workload of the captaincy was telling on Chappell and the four-Test Ashes series that followed the World Cup dampened his appetite for the game.

In the last England Test at the Oval, Chappell scored 192 from 367 balls to set up an apparent victory. However, England managed to bat for almost 15 hours to grind out a draw and Chappell announced his resignation from the captaincy on the final day of the match. In 30 Tests as captain, he scored 2,550 runs at an average of 50, with seven centuries. Remaining available for Test cricket, he played in the 1975/76 series against the West Indies under the captaincy of his brother Greg. Australia avenged their loss in the World Cup final by winning 5–1, claiming the unofficial title of best team in the world.

Throughout the course of the series, Chappell passed two significant milestones when he became the fourth Australian to make 5,000 runs in Test cricket and the first player to hold one hundred Test catches for Australia. During a dispute with the SACA over team selection, he threatened a "strike" action by the SA team. After the matter was resolved, Chappell led the side to the Sheffield Shield title for the second time in his career and shared the inaugural Sheffield Shield player of the season award with his brother Greg. He retired from first-class cricket at the end of the season, aged only 32.

In 1976, Chappell toured South Africa with Richie Benaud's International Wanderers team, released his autobiography Chappelli and was named as one of five Wisden Cricketers of the Year. He was hired to spend the summer of 1976/77 as a guest professional in the Melbourne district competition where he was paid more than he had been as Australian captain. During the season, he was involved in a famous altercation with a young English all-rounder who was in Victoria on a cricketing scholarship, Ian Botham. Both men have put forward vastly different versions as to what happened during the physical confrontation in a Melbourne pub.[69] The animosity between them continues and Channel Nine used it as a marketing ploy when Botham temporarily partnered Chappell as a television commentator during the 1998/99 season.

Approached to lead an Australian team in World Series Cricket (WSC), a breakaway professional competition organised by Kerry Packer for Channel Nine, Chappell signed a three-year contract worth A$75,000 in 1976. His participation was, "fundamental to the credibility of the enterprise". Chappell devised the list of Australian players to be signed, and was involved in the organisation and marketing of WSC. His central role was the result of, "years of personal disaffection with cricket officialdom", in particular Don Bradman. In WSC's debut season of 1977/78, Chappell hit the first Supertest century and finished fifth in overall averages. The prevalence of short-pitched fast bowling and a serious injury to Australian David Hookes led to the innovation of batting helmets; Chappell was one of the many batsmen to use one.

The constant diet of pace bowling undermined the confidence of some batsmen during WSC. Chappell's form fell away during the second season and he scored only 181 runs at 25.85 in four Supertests. During the last six days of the season, the WSC Australians lost the finals of both the limited-overs competition (to the West Indies XI) and the Supertest series (to the World XI), thus forfeiting the winner-takes-all prize money. After the latter match, Chappell vented his frustrations on World XI captain Tony Greig by refusing to shake his hand and criticising Greig's inconsequential contribution to his team's victory.

Convinced to return to official cricket when WSC ended, Chappell resumed as captain of SA in 1979/80, a decision he later regretted. It was a season too far for the increasingly irascible Chappell. Reported by an umpire for swearing in a match against Tasmania, he received a three-week suspension. In his first match after the ban, he was again reported for his conduct in a game against the touring English team. Given a suspended ban by the ACB, he was then selected for Australia's last three Tests of the season. His Test career finished with scores of 75 and 26 not out at the MCG against England in February 1980. In his final first-class match, SA needed to beat Victoria to win the Sheffield Shield. Although Chappell scored 112, SA lost the match and the shield.

Chappell was inducted into the Sport Australia Hall of Fame in 1986, the FICA Cricket Hall of Fame in 2000 and the Australian Cricket Hall of Fame in 2003. Two new grandstands at the Adelaide Oval were named the Chappell Stands; at the dedication ceremony in 2003, the SACA president Ian McLachlan called the Chappells, "the most famous cricketing family in South Australia". In 2004, the Chappell family was again honoured with the creation of the Chappell–Hadlee Trophy, an annual series of ODI matches played between Australia and New Zealand.

Chappell began working as a commentator for Channel Nine's cricket coverage in the 1980/81 season, a position he retained until the network lost the Australian home cricket rights to Channel 7 in April 2018. The greatest controversy of his first season was the Underarm Incident, which involved his two younger brothers in an ODI played between Australia and New Zealand at the Melbourne Cricket Ground. Chappell showed no fraternal bias and was vehement in his criticism of his brother Greg's tactic. He wrote in a newspaper column on the matter: "Fair dinkum, Greg, how much pride do you sacrifice to win $35,000?”