Reginald Alexander "Reggie" Duff (17 August 1878 – 13 December 1911) was an Australian cricketer who played in 22 Tests between 1902 and 1905. Duff made his Test debut along with Warwick Armstrong, against England at Melbourne in 1901–02 and scored 104 after being held back until No. 10 in the second innings due to a bad pitch. This innings was the first instance of a Test No. 10 scoring a hundred on debut and one of only four centuries from that low in the order by anyone. He was a specialist batsman and opened in the second innings of the next Test. He also scored a century in his last Test match, becoming the first batsman to score a century on Test debut as well as a century in his final Test.