Jeffery Lamar Williams Jr. (born August 16, 1991), known professionally as Young Thug, is an American rapper. Known for his eccentric vocal style and fashion, he is considered an influential figure in modern hip hop and trap music, and a pioneer of the mumble rap microgenre. Williams embarked on a musical career in 2011, releasing a series of mixtapes beginning with I Came from Nothing. In 2013, he signed with fellow Atlanta rapper Gucci Mane's 1017 Records and gained further attention and praise for his debut mixtape with the label, 1017 Thug, released in February of that year.

Williams first received mainstream recognition in 2014 for his singles "Stoner" and "Danny Glover," in addition to his guest appearances on numerous singles, including T.I.'s "About the Money", Tyga's "Hookah", and Rich Gang's "Lifestyle". That same year, he released a mixtape with Rich Gang titled Rich Gang: Tha Tour Pt. 1, and signed a solo recording contract with 300 Entertainment, an imprint of Atlantic Records. In 2015, he amassed a number of mixtapes to critical acclaim, including Barter 6 and two installments of his Slime Season series. Throughout 2016, Williams saw continued success with the release of his commercial mixtapes I'm Up, Slime Season 3, and Jeffery. In 2017, Williams guest performed on the worldwide hit "Havana" by singer Camila Cabello, which became his first number-one single on the Billboard Hot 100. The following year, he won the Grammy Award for Song of the Year for his contributions to Childish Gambino's "This Is America".

Williams' debut studio album, So Much Fun (2019) peaked atop the US Billboard 200 and yielded the Billboard Hot 100 top-20 singles "The London" (featuring J. Cole and Travis Scott) and "Hot" (featuring Gunna). The following year, his single "Go Crazy"—with Chris Brown, from their collaborative mixtape Slime & B (2020)—peaked at number three on the chart and became his first top-ten single as a lead artist. That same year, he peaked the chart once more for his guest appearance alongside M.I.A. on Travis Scott's single "Franchise". In 2021, he did so for a third time with his guest appearance alongside Future on Drake's "Way 2 Sexy". His second studio album, Punk was released in October of that year to continued success, followed by his third studio album, Business Is Business, in 2023. In addition to his solo career, he has released two compilation albums with his record label, YSL Records: Slime Language (2018) and Slime Language 2 (2021) to concurrent success; the latter debuted atop the Billboard 200.

Williams was arrested in May 2022 alongside 27 members of YSL and was charged with 63 counts of illegal substance trafficking or firearm possession and for violating the Georgia RICO Act. He was held without bail in the Fulton County Jail on remand and his trial began on November 2023. Williams was released in October 2024 after accepting a deal which saw him plead no contest to several charges: it resulted in him being sentenced to time served and 15 years of probation.