- Jack BruceFormed / started: 14 May 1943Split up / ended: 25 October 2014
- Jackie LomaxFormed / started: 10 May 1944Split up / ended: 15 September 2013
- Jaki WhitrenBorn in: SouthamptonDecade started: 1950s
- Jakko JakszykFormed / started: 8 June 1958Note: English musician, currently with King Crimson
- James BrownBorn in: BelfastDecade started: 1990s
- James DewarFormed / started: 12 September 1942Split up / ended: 16 May 2002
- James MorrisonFormed / started: 13 August 1984Note: UK singer
- James PrimeFormed / started: 3 November 1960Split up / ended: 19 June 2025
- James RoyalBorn in: EalingDecade started: 1940s
- Jamie MallenderDecade started: 1990sGenres: heavy metal music
- Janick GersBorn in: HartlepoolDecade started: 1970s
- Jason JamesBorn in: BridgendDecade started: 1980s
- Jason PerryBorn in: United KingdomDecade started: 1990s
- Jeff AllenDecade started: 1970sGenres: rock music
- Jeff BeckFormed / started: 24 June 1944Note: English rock guitarist
- Jeff SingerBorn in: ManchesterDecade started: 1970s
- Jeff WayneFormed / started: 1 July 1943Note: musician
- Jeffrey DunnBorn in: Newcastle upon TyneDecade started: 1970s
- Jerry ShirleyBorn in: Waltham CrossDecade started: 1960s
- Jesse HectorFormed / started: 17 July 1947Split up / ended: 6 May 2026
- Jet BlackFormed / started: 26 August 1938Split up / ended: 6 December 2022
- Jim CapaldiFormed / started: 2 August 1944Split up / ended: 28 January 2005
- Jim CapaldiBorn in: EveshamDecade started: 1960s
- Jim ReillyBorn in: BelfastDecade started: 1950s
- Jimmie O'NeillBorn in: GlasgowDecade started: 1970s
- Jimmy McCullochFormed / started: 4 June 1953Split up / ended: 27 September 1979
- Joe BrownFormed / started: 13 May 1941Note: UK singer, songwriter, guitarist
- Joe BrownBorn in: SwarbyDecade started: 1950s
- Joe CockerFormed / started: 20 May 1944Split up / ended: 22 December 2014
- Joe EganFormed / started: 18 October 1946Split up / ended: 6 July 2024
- Joe EganBorn in: PaisleyDecade started: 1940s
- Joe ElliottFormed / started: 1 August 1959Note: lead singer of Def Leppard
- Joe FaginBorn in: LiverpoolDecade started: 1940s
- Joe MeekFormed / started: 5 April 1929Split up / ended: 3 February 1967
- Joe StrummerFormed / started: 21 August 1952Split up / ended: 22 December 2002
- Joey MollandFormed / started: 21 June 1947Split up / ended: 1 March 2025
- John "Charlie" WhitneyBorn in: SkiptonDecade started: 1960s
- John BonhamFormed / started: 31 May 1948Split up / ended: 25 September 1980
- John Cooper ClarkeFormed / started: 25 January 1949Note: English poet
- John Du CannFormed / started: 5 June 1946Note: glam punk, UK
- John EntwistleFormed / started: 9 October 1944Split up / ended: 27 June 2002
- John GlascockFormed / started: 2 May 1951Split up / ended: 17 November 1979
- John GustafsonFormed / started: 8 August 1942Split up / ended: 12 September 2014
- John Harley WestonDecade started: 1960sGenres: rock music
- John LawtonFormed / started: 11 July 1946Split up / ended: 29 June 2021
- John LennonFormed / started: 9 October 1940Note: The Beatles
- John LodgeFormed / started: 20 July 1943Note: of the Moody Blues
- John LoweBorn in: West DerbyDecade started: 1950s
- John MarshallFormed / started: 28 August 1941Split up / ended: 16 September 2023
- John MartynFormed / started: 11 September 1948Note: British singer‐songwriter and guitarist
- John MayallFormed / started: 29 November 1933Split up / ended: 22 July 2024
- John McCoyBorn in: HuddersfieldDecade started: 1950s
- John MurphyFormed / started: 4 March 1965Note: English score composer
- John PorterBorn in: LichfieldDecade started: 1950s
- John RenbournFormed / started: 8 August 1944Split up / ended: 26 March 2015
- John RostillBorn in: BirminghamDecade started: 1960s
- John SteelBorn in: GatesheadDecade started: 1940s
- John SykesFormed / started: 29 July 1959Split up / ended: 21 December 2024
- John WeiderFormed / started: 21 April 1947Split up / ended: March 2025
- John WettonFormed / started: 12 June 1949Split up / ended: 31 January 2017
- John “Poli” PalmerFormed / started: 25 May 1943Split up / ended: 21 July 2025
- Johnny DevlinBorn in: RaetihiDecade started: 1950s
- Johnny KiddFormed / started: 23 December 1935Split up / ended: 7 October 1966
- Johnny KiddBorn in: WillesdenDecade started: 1950s
- Johnny McElhoneBorn in: GlasgowDecade started: 1960s
- Johnny WakelinBorn in: BrightonDecade started: 1970s
- Jon AndersonFormed / started: 25 October 1944Note: Yes/Jon & Vangelis
- Jon AstleyDecade started: 1950sGenres: rock music
- Jon HisemanFormed / started: 21 June 1944Split up / ended: 12 June 2018
- Jon KingBorn in: SouthwarkDecade started: 1950s
- Jon LeeFormed / started: 28 March 1968Split up / ended: 7 January 2002
- Jon LeeBorn in: NewportDecade started: 1990s
- Jon LordFormed / started: 9 June 1941Split up / ended: 16 July 2012
- Jon McClureBorn in: SheffieldDecade started: 2000s
- Jonny GreenwoodFormed / started: 5 November 1971Note: English musician and score composer
- Jonny MaudlingDecade started: 1980sGenres: heavy metal music
- Josang ThofroBorn in: Milton KeynesDecade started: 2000s
- Judy DybleFormed / started: 13 February 1949Note: British singer‐songwriter
- Julie DriscollFormed / started: 8 June 1947Note: English singer & actress
- Juliette JacksonBorn in: LondonDecade started: 1990s
- Justin HaywardFormed / started: 14 October 1946Note: of the Moody Blues
- Justin YoungBorn in: SouthamptonDecade started: 2000s