Brendon Barrie McCullum ONZM is a former New Zealand cricketer who captained the team in all formats. McCullum was renowned for his big hitting and quick scoring, notably setting a record for the fastest Test century. He is considered one of New Zealand's most successful batsmen and captained the side to the finals of the 2015 Cricket World Cup and 2009 ICC Champions Trophy.

Brendan McCullum is the former leading run scorer in Twenty20 International cricket and was the first player to score 2000 runs in T20Is. His innings of 123 against Bangladesh in the 2012 ICC World Twenty20 was the highest score made by a New Zealand cricketer in the format and he was the first New Zealander to score a triple hundred in a Test match - 302 runs against India in February 2014. Also in 2014, he also became the first New Zealander to score 1,000 Test runs in a calendar year and in his final Test match in February 2016 he scored the fastest Test century, reaching his hundred in 54 balls.

In March 2008, before facing England for the test series, McCullum was involved in the State Shield Final versus the Auckland Aces, scoring 170 runs for the Otago Volts to help beat the Aces at Eden Park's outer oval, and helped to chase down a daunting total of 7 for 310, he broke multiple State Shield batting records. He scored the fastest LA hundred off 52 balls, including 14 fours and 5 sixes. With 170 runs in the match, McCullum scored the highest score by any player in a domestic one-day match (Shell or State competitions) overtaking Blair Hartland's previous record.

In 2004, McCullum played in a Test series against England and scored 96 runs at Lord's. His maiden Test century came several months later when he scored 143 against Bangladesh. He fell just short of his second Test hundred in a game against Sri Lanka when dismissed one short of his hundred. His second century would later come with a run a ball 111 against Zimbabwe.

He was selected in the 20-man ICC World XI squad for the ICC Super Series in July 2005. On 20 February 2007, he scored 86 not out as New Zealand went on to be the first team to whitewash Australia in a three-match ODI series since 1997. During the innings he partnered with Craig McMillan to score 165, equalling the world record for a 6th wicket partnership. In December 2007, he scored 50 from just 19 balls against Bangladesh. He finished his innings with 80 runs from only 28 balls, including 9 fours and 6 sixes with a strike rate of 285.71.

In July 2008, McCullum scored his maiden ODI century, a 135-ball 166, against Ireland in the Associates Tri-Series in Scotland. His century, along with James Marshall's 161 is the highest ODI partnership for any wicket in Black Caps history and the second highest opening partnership in all ODIs. and Ross Taylor's 59, elevated New Zealand to 402, the highest and their only 400+ score for their team until date, and they won by 290 runs, setting a world record for the biggest margin of victory by runs, a record that stood until 2023.

In November 2009, against Pakistan at Abu Dhabi, McCullum scored his second ODI century of 131 to elevate New Zealand to 303 and win the match to level the series. In February 2010, during the only Test match against Bangladesh, he scored 185, which is the highest score ever by a New Zealand wicket-keeper in Test cricket. He was also involved in the record highest sixth-wicket partnership for New Zealand of 339 runs with Martin Guptill, missing out on the world record by just 12 runs.

In February 2010, McCullum became the second player to score a T20I hundred, finishing 116 not out, one run short of Chris Gayle's record of 117. On 4 May 2010 McCullum became the first player to score 1,000 T20 international runs. He achieved this feat playing against Zimbabwe in the 2010 ICC World Twenty20 at Guyana.

In 2014 at the Basin Reserve in Wellington, McCullum scored 302 runs in the third innings of the second test against India, becoming the first New Zealand batsman to score a triple-century. He shared a 352 run partnership with BJ Watling, then a record sixth wicket stand, rescuing New Zealand from a likely innings defeat. McCullum closed the innings at 680/8d, both the highest ever innings by New Zealand, and the highest ever third innings in Test cricket history.

In November 2014, McCullum took his first-ever wicket at test level, a caught-and-bowled of Pakistan's Sarfraz Ahmed during their second test. In November, McCullum scored a century on Day 2 of the third test against the same opposition, in which both teams decided to call off play on the day before as a tribute to Phillip Hughes, and hand-written P.H. under each player's squad number as a further mark of respect. He was bowled out on 202 after hitting eleven sixes in his innings, by far a record for New Zealand opening batsman.

On the first day of the Boxing Day Test at Hagley Oval, McCullum scored 195 in the first innings against Sri Lanka, which gave him 1000 test runs in a calendar year, becoming the first New Zealander to reach this milestone (1164 at the end of the match, with Kane Williamson at 929), and the fastest test century (in 74 balls), beating his own record against Pakistan in Sharjah. He fell 5 runs shy of his 4th 200+ scores in a calendar year. His 33 sixes in test cricket in a single calendar year is also a world record. It is also worth noting that New Zealand only played 9 test matches in 2014. He also helped to push New Zealand to score 429/7 on day one, the most runs New Zealand had ever scored in a single day of play in test cricket. It ended with an 8-wicket win, which made it 5 test wins out of 9 matches. For his performances in the 2014–15 season, Brendon McCullum won the Sir Richard Hadlee Medal.

McCullum also led New Zealand in the 2015 Cricket World Cup, which was co-hosted by New Zealand and Australia. On 20 February 2015, in New Zealand's third Pool A match against England, McCullum scored 77 runs off 25 balls, recording the fastest 50 in World Cup history (51 runs off 18 balls) and the 4th fastest fifty of all time. McCullum led the New Zealand team to their first World Cup final, scoring timely innings in the pool match against Australia and South Africa in the semi-final. The semi-final victory was New Zealand's first after six semi-final losses in the past. In the final against Australia, McCullum was bowled for a duck in just the first over of the match by Mitchell Starc, as New Zealand went on to lose to Australia by 7 wickets.

On 21 May 2015, McCullum started in his 93rd consecutive test, and batted in his preferred spot at No. 5. On 13 December 2015, on McCullum's 98th consecutive test start, he scored his 100th six hit in test cricket, tying the record set by Adam Gilchrist. In February 2016, McCullum started his 100th consecutive test, but was dismissed in both innings by Mitchell Marsh, making Marsh the second person since Jason Gillespie to dismiss him on both innings of 2 test matches.

On 20 February 2016, in his final test in his adopted home of Christchurch, McCullum became the only member left from the last Trans-Tasman Test in Christchurch in the pre-earthquake AMI Stadium. The third day of the test was the 5th anniversary of the 2011 Christchurch earthquake. He hit his 102nd career six to surpass Adam Gilchrist as the most prolific six-hitter in test cricket. He went on to score a century off 54 balls, beating the joint record by West Indian Viv Richards and Pakistani Misbah-ul-Haq for the fastest test century by 2 balls. He also became the second player since Jason Gillespie to score a hundred or more in his final test. McCullum also recorded the highest (170) runs scorer by the captain in farewell test and 1st captain to score a ton in farewell test. He also took four catches as a fielder at first slip, deputising for the injured Ross Taylor.

On 22 February 2016, McCullum played his last innings in a Test Match against Australia. He scored 25 off 27, when he was dismissed by Josh Hazlewood one ball after hitting him for a 6. McCullum was given a guard of honour upon entry onto the field, and was given a standing ovation once dismissed. Brendon McCullum on his retirement said that the time was right to quit international cricket and said that he hopefully left and brought some fun and enjoyment and some real culture back into the set-up in the time that he had as captain.

McCullum had the ability to play the Dilscoop (which was invented by Sri Lankan Tillakaratne Dilshan) or precisely the ramp shot, which involves the batsman squatting down and scooping deliveries back over the wicketkeeper's area. The two shots have their own distinction, where Dilscoop is played right above the wicket-keeper's head, but ramp shot can be played in sideways of the wicket-keeper as well. Playing this ramp shot in a Twenty20 International match in February 2010 in Lancaster Park, against Australia, he managed to hit Shaun Tait for two sixes in an over back over Brad Haddin's head, forcing Australia to set a back stop (the fielder near the boundary behind the wicketkeeper.

In the 2015 Queen's Birthday Honours McCullum was appointed an Officer of the New Zealand Order of Merit for services to cricket. He won the New Zealand Sportsman of the Year award in 2014, and then the Sport New Zealand Leadership Award in 2016. McCullum was appointed as head coach for both Trinbago Knight Riders and Kolkata Knight Riders in August 2019. Under his stewardship, Trinbago won their fourth Caribbean Premier League title in 2020, while Kolkata reached the Indian Premier League final in 2021.

In May 2022, he was appointed as a head coach of Test format for the England cricket team. His first assignment was a 3-Test home series against his home country New Zealand which they won with a clean sweep. This was followed by a win against India at Edgbaston, where England chased down a record 378 for the loss of only three wickets. The new attacking, positive intention approach, instigated by McCullum and captain Ben Stokes was labelled Bazball.

The South Africa cricket team toured England to play three Test matches in August 2022. England won the series win 2–1. In the winter of 2022 during England's tour of Pakistan, he coached England to the first ever whitewash of Pakistan in a home series. In May 2018, he briefly returned to rugby for a month playing for Matamata, a game he hasn't played since starting over Dan Carter in high school before retiring, citing diminishing knowledge of the game, and rugby fitness. McCullum currently invests in NZ thoroughbred bloodstock which is his true passion now fully retired from all cricket.