Jef is a Dutch-language masculine given name primarily used in Belgium. It is a short form of Jozef/Josef, used also in Breton. People with the name include:

• Jef Billings (born 1945), American figure skating costume designer
• Jef Boeke (born 1950s), American geneticist
• Jef Bruyninckx (1919–1995), Belgian film actor, editor and director
• Jef Caers (born 1970s), Belgian geostatistician
• Jef Colruyt (born 1958), Belgian businessman
• Jef Delen (born 1976), Belgian footballer
• Jef Demuysere (1907–1969), Belgian cyclist
• Jef Denyn (1862–1941), Belgian carillon player
• Jef Dutilleux (1876–1960), Belgian painter
• Jef Elbers (born 1947), Belgian singer, script writer, and political activist
• Jef François (1901–1996), Belgian Nazi collaborator
• Jef Gaitan (born 1986), Filipino actress
• Jef Geeraerts (1930–2015), Belgian writer
• Jef Geys (1934-2018), Belgian artist
• Jef Gilson (1926–2012), French pianist, arranger, composer and big band leader
• Jef Jurion (born 1937), Belgian footballer
• Jef Labes, American keyboardist
• Jef Lahaye (1932–1990), Dutch cyclist
• Jef Lambeaux (1852–1908), Belgian sculptor
• Jef Last (1898–1972), Dutch poet, writer, translator and cosmopolitan
• Jef Lataster (1922–2014), Dutch long-distance runner
• Jef Leempoels (1867–1935), Belgian painter
• Jef Lowagie (1903–1985), Belgian cyclist
• Jef Maes (1905–1996), Belgian composer and violist
• Jef Mallett (born 1962), American comics artist
• Jef Martens (born 1975), Belgian DJ known as "Basto"
• Jef McAllister (born 1956), American journalist, author and lawyer
• Jef Mermans (1922–1996), Belgian footballer
• Jef Murray (1960–2015), American fantasy artist and author
• Jef Neve (born 1977), Belgian pianist and composer
• Jef Nys (1927–2009), Belgian comic book creator
• Jef Planckaert (1934–2007), Belgian cyclist
• Jef Raskin (1943–2005), American human–computer interface expert
• Jef Scherens (1909–1986), Belgian cyclist
• Jef Tavernier (born 1951), Belgian politician
• Jef Valkeniers (born 1932), Belgian physician-neuropsychiatrist and politician
• Jef Van Campen (born 1934), Belgian post-impressionistic painter
• Jef Van Damme (born 1979), Belgian politician
• Jef van de Wiele (1903–1979), Belgian Nazi politician
• Jef Van Der Linden (1927–2008), Belgian footballer
• Jef Van der Veken (1872–1964), Belgian art restorer, copyist and art forger
• Jef Van Gool (born 1935), Belgian footballer
• Jef van Hoof (1886–1959), Belgian composer and conductor
• Jef Van Meirhaeghe (born 1992), Belgian cyclist
• Jef Vliers (1932–1995), Belgian footballer