Friðþjófur (variations: Fritiof, Frithiof, Fritjof, Frithjof, and Fridtjof) is a Scandinavian masculine given name derived from Old Norse: friðr + þjófr, transl. 'peace' and 'thief'. Bearers of the name include:

• The hero of Frithiof's Saga, an Icelandic saga finalized around 1300

• Frithjof M. Plahte (1836–1899), Norwegian merchant and landowner
• Frithjof Prydz (1841–1935), Norwegian judge
• Carl Frithjof Smith (1859–1917), Norwegian-German painter
• Fridtjof Nansen (1861–1930), Norwegian explorer
  • Fridtjof Nansen (disambiguation), things named in his honor
• Fritjof Heyerdahl (1879–1970), Norwegian engineer and industrial leader
• Frithjof Olsen (1882–1922), Norwegian gymnast
• Fridtjof Backer-Grøndahl (1885–1959), Norwegian pianist and composer
• Frithjof Olstad (1890–1956), Norwegian rower
• Frithjof Sælen (gymnast) (1892–1975), Norwegian gymnast
• Frithjof Andersen (1893–1975), Norwegian wrestler
• Fridtjof Knutsen (1894–1961), Norwegian journalist and crime novelist
• Fridtjof Paulsen (1895–1988), Norwegian speed skater
• Frithjof Lorentzen (1896–1965), Norwegian fencer
• Fridtjof Mjøen (1897–1967), Norwegian actor
• Carl Fridtjof Rode (1897–1984), Norwegian judge
• Frithjof Ulleberg (1911–1993), Norwegian footballer
• Frithjof Jacobsen (1914–1999), Norwegian diplomat
• Frithjof Tidemand-Johannessen (1916–1958), Norwegian designer and writer
• Frithjof Clausen (1916–1998), Norwegian wrestler
• Frithjof Sælen (writer) (1917–2004), Norwegian writer
• Fridtjof Frank Gundersen (born 1934), Norwegian jurist
• Leif Fritjof Måsvær (born 1941), Norwegian politician
• Frithjof Prydz (athlete) (1943–1992), Norwegian ski jumper and tennis player
• Fridtjof Røinås (born 1994), Norwegian racing cyclist
• Fridtjof Støre, singer for Norwegian band Albino Superstars (formed in 2004)

• Frithiof Holmgren (1831–1897), Swedish physician and physiologist
• Frithiof Mårtensson (1884–1956), Swedish wrestler
• Fritiof Domö (1889–1961), Swedish landlord and politician
• Fritiof Karlsson (1892–1984), Swedish politician
• Fritiof Nilsson Piraten (1895–1972), Swedish author
• Fritiof Svensson (1896–1961), Swedish wrestler
• Elof Fritjof Hillén (1893–1977), Swedish soccer player
• Frithiof Rudén, Swedish footballer
• Fritiof Billquist (1901–1972), Swedish film actor
• Tage Fritjof Erlander (1901-1985), Prime Minister of Sweden from 1946 to 1969
• Fritjof Lager (1905–1973), Swedish politician
• Fritiof S. Sjöstrand (1912–2011), Swedish physician and histologist
• Fritiof Enbom (1918–1974), Swedish railway worker
• Fritiof Andersson, title character of "Fritiof och Carmencita", a 1937 Swedish song written by Evert Taube
• Fritiof Björkén (born 1991), Swedish footballer

• Fritiof Andersen (1898–1954), Danish track and field athlete

• Frithiof Nevanlinna (1894–1977), Finnish mathematician

• SMS Frithjof (laid down 1890), German coastal defense ship
• Frithjof Henckel (born 1950), German rower
• Frithjof Schmidt (born 1953), German politician for the Greens
• Frithjof Kleen (born 1983), German sailor
• Frithjof Seidel (born 1997), German diver

• Frithjof Schuon (1907–1998), Swiss metaphysician

Norwegian descent

• Karl Fritjof Rolvaag (1913–1990), American politician

Swedish descent

• Fritiof Fryxell (1900–1986), American geologist and mountain climber

Austrian descent

• Frithjof Bergmann (1930–2021), German-American philosopher
• Fritjof Capra (born 1939), American physicist, ecologist, and systems theorist

• Fridtjof Island, lying in the Palmer Archipelago

• Friedhof (disambiguation)