- Jack E. VolderCitizenship: United StatesBorn: September 9, 1924
- Jacob BernoulliCitizenship: SwitzerlandBorn: December 27, 1654
- Jacqueline CiffréoCitizenship: FranceBorn: December 26, 1933
- Jacques E. BrandenbergerCitizenship: SwitzerlandBorn: October 19, 1872
- Jacques Johan MogendorffCitizenship: Kingdom of the NetherlandsBorn: December 12, 1898
- Jacques-Louis SoretCitizenship: SwitzerlandBorn: June 30, 1827
- Jakob BuchliCitizenship: SwitzerlandBorn: March 4, 1876
- James E. GunnCitizenship: United StatesBorn: October 21, 1938
- James M. EarlyCitizenship: United StatesBorn: July 25, 1922
- James M. RoeCitizenship: United StatesBorn: 1943
- James MellaartCitizenship: United KingdomBorn: November 14, 1925
- James Power GordonCitizenship: United StatesBorn: March 20, 1928
- Jaume NomenCitizenship: SpainBorn: June 23, 1960
- Jean Charles Galissard de MarignacCitizenship: SwitzerlandBorn: April 24, 1817
- Jean-Claude MerlinCitizenship: FranceBorn: September 3, 1954
- Jean-Marc PetitCitizenship: FranceBorn: 1961
- Jean-Marie SouriauCitizenship: FranceBorn: June 3, 1922
- Jean-Philippe de CheseauxCitizenship: SwitzerlandBorn: May 4, 1718
- Jerzy DobrzyckiCitizenship: PolandBorn: April 8, 1927
- Joan Pons i MoyàCitizenship: SpainBorn: 1955
- Joel PritchardCitizenship: United StatesBorn: May 5, 1925
- Johan LinnemannCitizenship: Kingdom of DenmarkBorn: June 4, 1830
- Johann Georg LiebknechtCitizenship: Holy Roman EmpireBorn: April 23, 1679
- Johannes SchmidtCitizenship: GermanyBorn: April 24, 1850
- Johannes StüblerCitizenship: AustriaBorn: 1958
- John Carlyle RavenCitizenship: United KingdomBorn: June 28, 1902
- John Hanning SpekeCitizenship: United Kingdom of Great Britain and IrelandBorn: May 3, 1827
- John Joseph MerlinBorn: September 17, 1735Occupation: watchmaker
- John M. PollardCitizenship: United KingdomBorn: October 25, 1941
- John Scott RussellCitizenship: United Kingdom of Great Britain and IrelandBorn: May 9, 1808
- John StringfellowCitizenship: United KingdomBorn: December 6, 1799
- Josef KřovákCitizenship: CzechoslovakiaBorn: October 12, 1884
- Josef MeixnerCitizenship: GermanyBorn: April 24, 1908
- Josef SzombathyCitizenship: Austrian EmpireBorn: June 11, 1853
- Josep Comas i SolàCitizenship: SpainBorn: December 17, 1868
- Joseph AspdinCitizenship: Kingdom of Great BritainBorn: December 25, 1778
- Joseph LuftCitizenship: United StatesOccupation: social psychologist
- Joseph OesterléCitizenship: FranceBorn: 1954
- Joseph PolchinskiCitizenship: United StatesBorn: May 16, 1954
- Joseph PoussotBorn: December 6, 1861Occupation: inventor
- Joseph RhedenCitizenship: AustriaBorn: April 5, 1873
- Joseph Valentin BoussinesqCitizenship: FranceBorn: March 13, 1842
- Josephine SalmonsCitizenship: South AfricaBorn: February 1901
- Jules RichardCitizenship: FranceBorn: December 19, 1848
- Julio ArbosaBorn: August 22, 1939Occupation: activist
- János KelemenCitizenship: HungaryBorn: 1951
- Jérôme Eugène CoggiaCitizenship: FranceBorn: February 18, 1849
- Józef MarcinkiewiczCitizenship: PolandBorn: March 30, 1910
- JōeCitizenship: JapanBorn: 643