Billy Slater is an Australian former professional rugby league footballer who played in the 2000s and 2010s. Slater is the current coach of the Queensland Maroons, whom he coached to victories in the 2022 and 2023 State of Origin series. Widely regarded as the greatest fullback of all time, Slater was known for his incredible vision, game reading, and try-scoring feats.

Slater was born in Nambour, Queensland, Australia on 18 June 1983. He began playing rugby league football for the Brothers club in Innisfail, Queensland. A North Queensland Cowboys fan growing up, he never made a representative side with the club. At sixteen years of age, Slater left school at Innisfail State High School and decided to follow his personal passion for thoroughbred racing, working initially in Sydney for six months as a roustabout for racehorse trainer Gai Waterhouse.

Slater commenced playing for the Melbourne Storm in 2003. In Round 1 of the 2003 NRL season, Slater made his first grade NRL debut for the Melbourne Storm against the Cronulla-Sutherland Sharks at Remondis Stadium. After a stellar début season saw him crowned Dally M Rookie of the Year (although the awards that year were cancelled in protest), Slater was the Storm's highest try scorer in the 2003 NRL season with 19 tries in their 26 matches.

Slater made his debut on the wing for Queensland in game one of the 2004 State of Origin series. His second try in Game II is considered one of the great individual Origin tries. Trailing 12–10, Slater latched onto a grubber kick from Darren Lockyer, chip-kicked the ball over Blues fullback Anthony Minichiello, regathering the ball and scoring in QLD's 22–18. Slater played 22 matches and scored 14 tries for the Storm in the 2014 NRL season. He was named in the Kangaroo squad to tour Europe but injury prevented him from joining in the tour.

Slater again impressed in his third NRL season. Once again Slater was picked for the 2005 Queensland State of Origin team, this time at his preferred position of fullback. Slater was dumped from the Queensland side for the deciding third game in Brisbane which led to outrage from some Maroons fans. With injuries and suspensions, Slater had to wait three years for another chance at State of Origin. Slater continued his brilliant form throughout 2005, topping the try scoring charts with 20 tries in 21 matches for the Storm.

Slater had a less successful 2006 season, with injury and a seven match suspension for kicking Wests Tigers prop John Skandalis. Billy Slater played at fullback in his first Grand Final, succumbing 15–8 to a red hot Broncos team. Slater was part of the Melbourne Storm 2007 NRL Grand Final winning team at Fullback, defeating the Manly-Warringah Sea Eagles 34–8, which was later stripped from them for cheating the salary cap. Slater played in 23 matches and scored 12 tries for the Storm in the 2007 NRL season. Slater won the Storms Back of the Year Award. In the post season Slater was named at Fullback in the Melbourne Storm Team of the Decade.

Slater's start to the 2008 season can be described as nothing short of sensational. He scored 3 tries in Melbourne's 32–18 Round 1 win at Etihad Stadium. Slater's form was rewarded when he was selected at fullback for the Australian national team in the Centenary Test against New Zealand, displacing the incumbent Brett Stewart. In August 2008, Slater was named in the preliminary 46-man Kangaroos squad for the 2008 World Cup. Slater capped off a brilliant year by winning the Rugby League World Golden Boot Award as the best player in the world. In 2008 he also received the Rugby League International Federation's International Player of the Year award.

Slater was selected for Australia in the 2009 Anzac Test match at fullback against New Zealand at Suncorp Stadium in the Kangaroos' 38–10 redemption win over the Kiwis after losing the World Cup to them in England. Slater played 150th NRL career match in the Storms 20–8 win. Melbourne finished the season 4th on the NRL table and avenged their 2008 Grand Final loss to Manly by defeating them 40–12 in the first week of the finals at Etihad Stadium. In the next week, the Grand Final was won by the Melbourne Storm over the Parramatta Eels 23–16. Again this was also stripped from Melbourne for systematic salary cap cheating. Slater scored a try and was judged best on ground, earning the Clive Churchill Medal.

Despite Melbourne being stripped of their 2007 and 2009 premierships due to the discovery of a salary cap breach, Slater was allowed to keep his Clive Churchill Medal. Slater was also involved in Queensland's 3–0 whitewash in the 2010 State of Origin series and received the Wally Lewis Medal for player of the series. Slater played in 22 matches and scored 10 tries in the Storms drama filled 2010 NRL season in which they were stripped all premiership points, and barred from collecting anymore (Including ones earned from byes) on 22 April as a result of their salary cap breaches.

In 2011 Slater scored two where he broke the record for the number of tries scored for Melbourne Storm with 114 tries, previously held by Matt Geyer. Slater played in all three 2011 State of Origin matches, as fullback for the Queensland Maroons. Slater scored in the last 10 minutes of Game 1 in the Queensland's 16–12 win in Brisbane, and scored in the last 15 minutes of Game 3 in QLD's 34–24 series winning match in Brisbane. Slater was awarded the 2011 Dally M Medal for best and fairest player of the year in the NRL despite being bundled out by the NZ Warriors in the Preliminary Final at AAMI Park.

In 2012, Slater started the year scoring 9 tries in 5 games, including 2 tries per game in the opening 4 rounds of the season. Slater finished the 2012 NRL season with him scoring 16 tries in 21 matches for the Storm, which made him the highest fullback try scorer in the NRL with 140 tries, going past previous holder Rhys Wesser. Slater played all three games of the 2013 State of Origin series in which Queensland extended their record for consecutive series victories to eight. Slater was the Storm's highest tryscorer in the 2013 NRL season with 18 tries in 24 matches.

In Round 2 2015 against the Penrith Panthers, Slater reached a milestone of having played 250 games for Melbourne Storm in the 18–17 win at AAMI Park. Billy Slater eclipsed Andrew Ettingshausen tryscoring record with 166 tries, Slater now currently being third in the highest tryscorer ranks. Injury affected his 2015 season, only playing in 7 matches and scoring two tries for the Storm. In 2016 he was then later again ruled out for 6–8 months with injury.

Playing his first NRL final series appearance since 2014 (despite missing the 2015 and 2016 play-offs due to shoulder injuries) and during the first week of the NRL play-offs final series; Slater played a key part in his side's 18–16 win over the Parramatta Eels at AAMI Park, scoring a try (his 180th NRL career try) in the 2nd half of the game which resulted him drawing level to former Manly Sea Eagles player Steve Menzies as the game's all-time second-equal highest top try-scorer. The Storm progressed through to the Grand Final and resulted him to move past Steve Menzies as the game's stand-alone second highest top try-scorer (behind another former Manly Sea Eagles player Ken Irvine, who had scored 212 tries).

Playing in the Grand Final at ANZ Stadium on 1 October; Slater produced an outstanding performance guiding the Melbourne Storm to win the 2017 NRL Premiership (their first Premiership since 2012), beating the North Queensland Cowboys 34–6. Following the game, he received the Clive Churchill Medal as the best player on the field. In 2018, he returned to the field in Round 2, playing his 300th NRL Career game. Slater announced his intentions to retire from representative football after the 2018 State of Origin series and was yet to make a decision on playing only at the club level in 2019.

In August, Slater announced that he would be retiring from the NRL at the end of the 2018 season.[190] He played his final game, a grand final loss to the Sydney Roosters, on 30 September 2018. In August 2019, Slater was chosen at Fullback in the Queensland Maroons team of the decade.

Billy was selected as the Queensland Maroons Head Coach on 24 September 2021 on a two-year deal. Slater coached the Queensland Maroons to a shock series victory in the 2022 State of Origin series. He followed this up with victory in the 2023 State of Origin series. In September 2023, he signed a three-year extension to coach the team. In August 2024, the National Rugby League announced that Slater was an inductee into the National Rugby League Hall of Fame. Slater, who was ascribed Hall of Fame number 122, was amongst eleven male players in the 2024 Class.