Brett Morris is an Australian former professional rugby league footballer who played on the wing and as a fullback for the St George Illawarra Dragons, Canterbury-Bankstown Bulldogs and the Sydney Roosters in the NRL, State of Origin and Australia at international level. Morris is the fifth highest try scorer for in premiership history, with 176 tries (only behind Ken Irvine's 212 tries, Billy Slater's 190 tries, Alex Johnston’s 197 tries and Steve Menzies’ 180 tries).

Morris was born at St George Hospital in Kogarah, New South Wales, but went to school in Kiama, New South Wales. He played his junior rugby league with the Kiama Knights alongside his twin brother Josh Morris before signing with the St. George Illawarra Dragons. Morris is the son of St. George Dragons, NSW and Australian rugby league representative Steve Morris, twin brother of Josh Morris who played for the Roosters and Dragons in the NRL and was previously a state and national representative.

In Round 9 of the 2006 NRL season, Brett Morris made his first grade debut for the St. George Illawarra, playing against Cronulla on the wing. In the 2007 Round 4 match against Cronulla, Morris then played his first match alongside his twin brother Josh Morris for St. George. 2009. BMoz had an outstanding 2009 NRL season for the Dragons, including scoring four tries in round 9 against the North Queensland Cowboys in the club's 24–20 loss, a hat trick in Round 11 against Cronulla, and another hat-trick in Round 26 against the Parramatta Eels. He was named Dally M highest tryscorer of the year with 25 tries in 24 matches.

Morris was selected to play for Australia in the 2009 Four Nations tournament. He crossed six times in 4 matches to finish the tournament as top try-scorer, including scoring 2 tries in the 46-16 Final win over England. Morris kept up his try-scoring form early in 2010 season, scoring a hat-trick in Round 2 against his twin brother's team, Canterbury. Morris made his debut for New South Wales in Game I of the 2010 State of Origin series, playing on the wing in the Blues 28–24 loss at ANZ Stadium. He played all three matches of the series in the NSW 3–0 series loss. Morris finished the 2010 NRL season as the Dragons highest tryscorer with 20 tries in 25 matches. He was later selected for Australia 2010 Four Nations squad, playing in 4 matches and scoring 3 tries in the tournament, including playing on the wing in the loss against New Zealand in the Final.

In 2011 Morris played his 100th NRL match. He scored 10 tries in his 21 matches for the Dragons. In 21 February 2012, Morris re-signed with St. George Illawarra for a further three years until the end of the 2015 NRL season. Morris was shifted from his usual position on the wing to fullback by coach Steve Price. He also played at fullback for NSW Country Origin in their 24–22 loss to NSW City in Mudgee. Morris played a match for the NSW in the 2012 State of Origin series, playing in game III on the wing and scoring a try in the Blues 21–20 loss at Suncorp Stadium. Morris finished the 2012 NRL season as the Dragons highest tryscorer with 14 tries in 23 matches.

Morris played for Australia on the wing and scored a try in the 2013 Anzac Test 32–12 victory against New Zealand at Canberra. He was selected to played in all of the NSW' three matches and scored a try in the 2013 State of Origin series. In round 25, against the Parramatta Eels, Morris played his 150th NRL career match. Morris was selected for the Australia Kangaroos 24-man squad for the 2013 World Cup. Morris played in 5 matches and scored 8 tries, which including scoring 4 tries against the USA Tomahawks in the Kangaroos' 62–0 win.

Brett Morris finished the 2014 NRL season with him playing in 18 matches and scoring 14 tries for the Dragons. In Round 1, 2015, Morris made his club debut for Canterbury at fullback, scoring a try in the 24–18 loss to Penrith. Morris finished his first year with Canterbury playing in 16 matches and scoring 9 tries in the 2015 NRL season. In March 2016, Morris was ruled out for four months with a knee injury. Morris made his return in Round 16, playing against the Brisbane Broncos and scoring a hat trick of tries in the 40–14 win at ANZ Stadium. He finished the 2016 NRL season strongly, playing in 11 matches and scoring 10 tries for the Bulldogs.

In Round 4, against Manly, Morris played in his 200th NRL career match in Canterbury's 36–0 loss at Brookvale Oval. On 18 July Morris announced his retirement from representative rugby league. He had played 15 origins for NSW and had an "incredible record" of 23 tries in his 18 matches for Australia. In 2018, Morris signed a contract to join the Sydney Roosters for the 2019 NRL season.

Morris scored a hat-trick on his Roosters debut in the World Club Challenge victory over Wigan on in February 2019. On 21 August, Morris was voted as one of the best players of the decade in the NRL team of the decade announcement which spanned from the 2010 to 2019 seasons. Premiership-winning coaches Phil Gould, Craig Bellamy, Trent Robinson and Ricky Stuart were also part of the panel along with Hall of Famers Peter Sterling, Darren Lockyer, Danny Buderus and Laurie Daley.

Brett Morris played on the wing in the club's 2019 NRL Grand Final victory over Canberra at ANZ Stadium. Morris made a total of 15 appearances and scored 7 tries in the 2019 NRL season. Brett's twin brother, Josh, requested to be released by Cronulla and then joined the Sydney Roosters from Round 3 of 2020. In round 7 of the 2020 NRL season, Brett Morris scored a hat-trick against one of his former clubs as the Sydney Roosters defeated St. George Illawarra. Morris made a total of 17 appearances and scored 12 tries in the 2020 NRL season as the club fell short of a third successive premiership.

In Round 1 of the 2021 NRL season, Morris scored a hat-trick in the Sydney Roosters 46–4 victory over the Manly Sea Eagles at the SCG. The following week, Morris scored another hat-trick in the Sydney Roosters 40–6 victory over the Wests Tigers. Morris became the first player in history to score consecutive hat-tricks in the opening two rounds of the competition. Morris was taken from the field in the 77th minute of the Sydney Roosters 38–4 victory over Newcastle with an ACL injury. Sydney Roosters coach, Trent Robinson stated that he believed the injury may have ended Morris' career. He announced his retirement from playing in June 2021. Morris was announced as assistant coach for 2022 for the Sydney Roosters. In 2024, Morris was announced as the NSW Cup coach for the Sydney Roosters.