JJ or jj may refer to:
JJ Lin (traditional Chinese: 林俊傑; simplified Chinese: 林俊杰; pinyin: Lín Jùn Jié) is a Singaporean singer, songwriter, record producer and actor based in Taiwan.
JJCC (pronounced J-J-C-C, Hangul: 제이제이씨씨) is a six-member South Korean hip-hop boy group formed under the management of Jackie Chan Group Korea.
John Joseph Feild (born 1978), known professionally as JJ Feild, is a British-American actor.
Juan José Rendón Delgado (born 1964 in Caracas, Venezuela), known professionally as JJ Rendon, is a non-progressive Latin American political consultant, psychologist and political activist.
Jyrki Juhani Järvilehto (Finnish pronunciation: [ˈjyrki ˈjærvilehto]; born 31 January 1966 in Espoo), better known as "JJ Lehto", is a Finnish racing driver.
JJK Jyväskylä (JJK) is a Finnish football club, based in Jyväskylä. It currently plays in the Finnish second highest league Ykkönen.
JJB Sports plc (stylized as JJb sports) was a British sports retailer. On 24 September 2012, shares in JJB Sports were suspended, and the firm called in administrators.
JJ Project (Korean: 제이제이 프로젝트) is a South Korean pop duo, consisting of JB (제이비) and Jinyoung (진영). They were formed by JYP Entertainment and released their first single "Bounce" in May 2012. They debuted as a part of GOT7 in January 2014.