Nathan Michael Lyon (born 20 November 1987) is an Australian international cricketer. He made his Test debut in 2011 and plays domestic cricket for New South Wales. Lyon is an off-spin bowler and a lower-order right-handed batsman. Considered the most successful Australian off-spin bowler of all time, Lyon holds the record for the most Test wickets taken by an Australian off-spin bowler, passing Hugh Trumble's 141 wickets in 2015. In January 2021, Lyon played in his 100th Test match during Australia's series against India. As of 2025, Lyon is Australia's third highest Test wicket taker of all time and ranks seventh among all international players in Test cricket with more than 500 wickets.

Lyon has achieved a number of honours for his performances. He has been named in the ICC Test Team of the Year three times and was the recipient of the Shane Warne Men's Test Player of the Year award in 2019 and 2024. Lyon was a member of the Australian team that won the 2021–2023 World Test Championship.

Lyon was born in Young, New South Wales, to Stephen and Bronwyn Lyon. He moved from Young to Canberra as a teenager where he went on to play for ACT Cricket's under-17s and under-18s representative teams. Lyon played for Western Districts and University of Canberra Cricket Club in ACT Grade cricket and debuted for the ACT Comets in 2008 in the Cricket Australia Cup against the South Australian Second XI where he claimed a wicket on day one. During his time with Comets, Lyon was mentored by captain and later captain-coach, Mark Higgs, who helped him in his spin bowling, getting his bowling action right as well as the tactical side including what lines to bowl and fields to set. After Lyon left the Comets he continued to keep in contact with Higgs in regards to the game.

In 2010, Lyon moved to Adelaide and worked as a member of the ground staff team at the Adelaide Oval. He played for the Prospect Cricket Club in the South Australian Grade Cricket League while continuing playing for the Comets in the Futures League. After Lyon's performance in the 2010 Futures League Twenty20 in December for the Comets in Melbourne which South Australia's Twenty20 coach Darren Berry witnessed he was selected to play for the Southern Redbacks in the KFC Twenty20 Big Bash.

In 2010–11 KFC Twenty20 Big Bash Lyon was the leading wicket-taker where the Redbacks went on to win the competition. Lyon went on to play for South Australia in the Sheffield Shield and the Australian domestic limited-overs competition. In the same year he was selected to represent Australia A in Zimbabwe where he took 11 wickets in the tri-series to be named man of the series. Lyon signed to play in the inaugural season of the Big Bash League for the Adelaide Strikers.

In May 2017 it was announced that Worcestershire had signed Lyon as a replacement for compatriot John Hastings, who was competing in the ICC Champions Trophy. On 15 November 2017, during the final moments of the Sheffield Shield match against Queensland at the Allan Border Field, Lyon was involved in a bizarre incident, burning a piece of toast in the dressing room and causing the smoke alarm to go off, which brought the fire services to the ground and stopped play for 30 minutes.

In November 2019, Lyon signed for Hampshire as their overseas player for the 2020 season in Championship cricket in England. However, this deal was later cancelled due to the COVID-19 pandemic. In February 2021, during the 2020–21 Sheffield Shield season, Lyon took his 600th first-class wicket.

In August 2023, the Melbourne Renegades announced they had signed Lyon on a three-year deal for the Big Bash League starting with the 2023/24 season.