People and fictional characters [link]

Janet Jackson, an American singer and actress
Javed Jaffrey, an Indian actor
JJ Lin, A Chinese-Singaporean singer-songwriter
Lil' JJ, American stand-up comedian
J. J. Abrams, American film and television producer, writer, actor, composer and director
J.J. Burnel Anglo-French musician (The Stranglers and solo)
J.J. Cale, an American songwriter and musician
J.J. Jackson, American soul musician
J.J. Johnson, American jazz trombonist
JJ Lehto, Finnish racing driver
JJ Osbun, American Entertainment Industry professional
JJ Valaya, Indian Couturier
Janis Joplin, American singer, songwriter and music arranger
Jaromír Jágr, Czech hockey player
Jay-J, an American house DJ and producer
Jay-Jay Johanson, a Swedish musician and songwriter
Jordan Johnson, a homosexual adult film star
Joshua Jackson, Canadian-American actor
Jeff Jarrett, American professional wrestler
Jelena Janković, Serbian tennis player and a former no.1 tennis player in the World
Jenna Jameson, American porn actress
Jermaine Jackson
Jessie J, English musician
Jimmie Johnson, NASCAR Sprint Cup Driver
Joe Jonas, American singer, part of the Jonas Brothers
Joey Jordison, American drummer for metal band, Slipknot
Josh Johnson, Florida Marlins Major League Baseball pitcher
Jovan Jovanov, Macedonian singer
Judge Judy, American television judge of an eponymous programme
Junaid Jamshed, Pakistani singer
J.J. Redick, NBA Player for the Orlando Magic
Justo Justo, Filipino columnist and playwright

J. Jonah Jameson, a Marvel Comics character
Jet Jaguar, a character in the Godzilla film series
J. J. Evans (James Evans Jr.), a character in the 1970s television show Good Times
JJ Jones, a character from Skins
Jennifer "JJ" Jareau, a character in the television show Criminal Minds, portrayed by A.J. Cook
J.J., a "creature" from Resident Evil 4

Entertainment [link]

JJ (video game), a video game developed and published by Square Co., Ltd.
Jay Jay the Jet Plane, a CGI children's television cartoon fiction series
"JJ" (Skins episode), an episode of the teen drama Skins
- "JJ" (Skins series 3), an episode of the teen drama Skins from series 3
- "JJ" (Skins series 4), an episode of the teen drama Skins from series 4
Jay Jay, a 2003 Tamil film
Triple J, an Australian radio station formerly known as Double Jay with the callsign 2JJ
Jesus Jones, a British band
JJ (band), a band featuring Jan Johnston from the early 1990s (Columbia Records)
jj (band), a Swedish band
JJ (magazine), a fashion magazine

TAM Airlines (TAM Linhas Aéreas), a Brazilian airline whose IATA code is JJ
A defunct line on the New York City Subway, now called the J
Jason Jr. (ROV), a remotely operated vehicle (ROV) that belongs to the Woods Hole Oceanographic Institution (WHOI)

Brassiere cup size, JJ in the UK
Johnson and Johnson, a large US company, owner of the domain JJ.com
Two or more judges, in court reporting (e.g. "Smith and Jones JJ"; singular J)