2NE1 (Korean: 투애니원; RR: Tuaeniwon, IPA: [tʰu.ɛ.ni.wʌn]) is a South Korean girl group formed by YG Entertainment in 2009. The group consists of Bom, CL, Dara, and Minzy. Known for their musical experimentation, fashion, and stage presence, they are a leading figure of the Korean Wave and among the most influential K-pop girl groups of all time. They are recognized for expanding girl group styles in the Korean music industry, which in turn broke stereotypes of K-pop.

The group was introduced in March 2009 after appearing on the promotional single "Lollipop" alongside labelmate BigBang. 2NE1 rose to prominence with the release of their debut eponymous extended play (EP) that same year, which featured the singles "Fire" and "I Don't Care". They followed with their debut album To Anyone (2010), and their second self-titled EP (2011) produced the chart-topping singles "Don't Cry", "Lonely", "I Am the Best", and "Ugly". They embarked on the New Evolution Global Tour in 2012, which is the first world tour by a Korean girl group; a show at the Prudential Center in New Jersey was named the second best concert of that year by The New York Times. Their second and final album, Crush (2014), was both the first album by a Korean artist to appear within the top 100 on the US Billboard 200 and the highest charting Korean album for two years.

By the end of 2014, 2NE1 amassed a total of nine number-one songs on the Gaon Digital Chart, becoming the group with the most number-one singles in South Korea at the time. Following a two-year hiatus, in 2016, Minzy departed the group and YG Entertainment announced their disbandment. Their final single, "Goodbye", was released in January of the following year. They made a surprise reunion performance at Coachella 2022, and in 2024, announced a reunion under YG. They embarked on the Welcome Back Tour that same year.

2NE1 have won numerous accolades throughout their career, including eleven Cyworld Digital Music Awards, nine Melon Music Awards, and ten MAMA Awards; they were the first artists to receive all three daesangs (grand prizes) at the latter within two years of their debut. They have sold over 66 million digital and physical records worldwide, making them one of the best-selling girl groups of all time.