Karl (also Carl) is an originally Germanic variant of the male given name Charles, meaning "free man". For further details on origin and meaning, see Churl and Charles.
Notable people with the name include:
- Karl der Große (German for 'Charles the Great'), also known as Karolus Magnus in Latin and Charlemagne in French, 747–814), a Frankish King and the first Emperor of the Holy Roman Empire
- Karl, Truchsess von Waldburg (1548–1593), Imperial minister
- Karl, Count Chotek of Chotkow and Wognin (1783–1868), Austrian chancellor, Government President and school reformer of Bohemia
- Karl, Duke of Schleswig-Holstein-Sonderburg-Glücksburg (1813–1878), German duke
- Karl, Prince of Isenburg-Büdingen (1838–1899), head of the German house of Isenburg and Büdingen
- Karl, Freiherr von Prel (1839–1899), German philosopher and writer on mysticism and the occult
- Karl I of Austria (1887–1922), the last Emperor of Austria
- Karl, 8th Prince of Löwenstein-Wertheim-Rosenberg (1904–1990), German Roman Catholic nobleman
- Karl Abraham (1877–1925), German psychoanalyst
- Karl Albrecht (1920–2014), German entrepreneur and billionaire
- Karl Auerbach (born 1949), computer scientist
- Karl Barth (1886–1968), seminal Swiss Reformed Theologian
- Karl Bartos (born 1952), German musician
- Karl Becker (general) (1879–1940), German engineer and officer
- Karl Becker (painter) (1820–1900), German painter
- Karl Becker (philologist) (1775–1849), German philologist
- Karl Beckersachs (1886–1951), German actor
- Karl Benz (1844–1929), German engineer
- Karl Berggren, American electrical engineer
- Karl August Leopold Böhm (1894–1981), Austrian conductor
- Karl von In der Maur (1852–1913), Austrian statesman
- Karl Blossfeldt (1865–1932), German artist
- Karl Böhm (1894–1981), Austrian conductor
- Karl Bonatz (1882–1951), German architect
- Karl Brandt (1904–1948), German Nazi SS physician executed for war crimes
- Karl Briullov, Russian painter
- Karl Brooks (born 2000), American football player
- Karl Brugger (1941–1984), a German foreign correspondent for and author
- Karl Chmielewski, German Nazi SS concentration camp commandant
- Karl Chua (born 1978), Filipino economist
- Karl Cook (born 1990), American show jumper
- Karl Dall (1941–2020), German comedian and singer
- Karl Davies (born 1982), English actor
- Karl Denke (1860–1924), prolific and cannibalistic German serial killer
- Karl Ludwig Diehl (1896–1958), German actor
- Karl Dönitz (1891–1980), German admiral
- Karl Drews (1920–1963), American baseball player
- Karl Duldig (1902–1986), Austrian-Australian sculptor
- Karl Etlinger (1879–1946), German actor
- Karl Farmer (born 1954), American football player
- Karl Fazer (1866–1932), Finnish businessman and sport shooter
- Karl Fritzsch (1903–1945), German Nazi SS concentration camp commandant who was the first to use Zyklon B for mass murder
- Karl Gebhardt (1897–1948), German Nazi SS physician who conducted criminal medical experiments, executed for war crimes.
- Karl Göbel (1900 – 1945) Nazi Germany general
- Karl Green (1947–) British musician, bass player for British pop group Herman's Hermits.
- Karl Hammes (1896–1939), German operatic baritone and fighter pilot
- Karl Hannemann (1895–1953), German actor
- Karl Harst (1492–1563), German diplomat and assistant of Erasmus
- Karl Amadeus Hartmann (1905–1963), German composer
- Karl Haushofer (1869–1946), German geopolitician
- Karl Hess (1923–1994), American comedian
- Karl Hoblitzelle (1879–1967), American theater owner and philanthropist
- Karl-Friedrich Höcker (1911–2000), German Nazi SS concentration camp officer and war criminal
- Karl Holz (Nazi) (1895–1945), German Nazi
- Karl Jacobs (born 1998), American streamer and YouTuber
- Karl Jaspers (1883–1969), German philosopher
- Karl Joseph (born 1993), American football player
- Karl Kalkun (1927–1990), Estonian actor
- Karl Kassulke (1941–2008), American football player
- Karl Heinrich Kaufhold (1932–2020), German economic historian
- Karl Keating, (born 1950) Catholic apologist
- Karl Kneidinger (1882–1952), Austrian actor
- Karl-Otto Koch (1897–1945), German Nazi commandant of concentration camps
- Karl Kraus (writer) (1874–1936), Austrian writer
- Karl Christian Friedrich Krause (1781–1832), German philosopher
- Karl Kruszelnicki (born 1948), Australian television and radio personality
- Karl Künstler (1901–1945), German Nazi SS concentration camp commandant
- Karl Lagerfeld (1933–2019), German fashion designer
- Karl Landsteiner (1868–1943), Austrian biologist and physician
- Karl Lauterbach (born 1963), German Federal Minister of Health
- Karl Lehmann (1936–2018), German prelate of the Catholic Church, Bishop of Mainz from 1983 to 2016
- Karl Leo Heinrich Lehmann (1894–1960), German-born American art historian, archaeologist, and professor
- Karl Linnas (1919–1987), Estonian Nazi concentration camp commandant
- Karl Lucas (born 1972), English actor and comedian
- Karl Malden (1912–2009), American actor
- Karl Malone (born 1963), American basketball player
- Karl Maron (1903–1975), German politician
- Karl Marx (1818–1883), Prussian philosopher, father of historical materialism
- Karl Mecklenburg (born 1960), American football player
- Karl Möckel (1901–1948), German Nazi SS officer at Auschwitz concentration camp executed for war crimes
- Karl Moik (1938–2015), Austrian television presenter and singer
- Karl Nehammer (born 1972), Austrian politician
- Karl Olive (born 1969), French sports journalist and politician
- Karl Olson (1930–2010), American baseball player
- Karl von Oberkamp (1893–1947), German SS commander executed for war crimes
- Karl Pearson (1857–1936), English statistician
- Karl Pilkington (born 1972), English podcaster, author and former radio producer
- Karl Platen (1877–1952), German actor
- Karl Popper (1902–1994), Austrian/British philosopher
- Karl Power, British prankster
- Karl Rahm (1907–1947), German SS officer, commandant of the Theresienstadt concentration camp executed for war crimes
- Karl Rapp (1882–1962), German engineer
- Karl "Tuffy" Rhodes, American baseball player
- Karl Rove (born 1950), American political advisor
- Karl Roy (1968–2012), Filipino rock singer
- Karl Schiewerling (1951–2021), German politician
- Karl Silfverberg (1899–1978), Swedish Air Force major general
- Karl Heinz Schnell (1915–2013), German jet pilot during WW II
- Karl Eberhard Schöngarth (1903–1946), German Nazi SS war criminal, executed for war crimes
- Karl Schädler (1804–1872), President of the Landtag of Liechtenstein
- Karl Shiels (1971–2019), Irish actor
- Karl Schlyter (1879–1959), Swedish jurist and politician
- Karl Singer (born 1943), American football player
- Karl Söllner, (1903–1986), German-Austrian chemist
- Karl Stefanovic (born 1971), Australian television presenter
- Karl Steubl (1910–1945), Nazi war criminal
- Karl Streibel (1903–1986), German Nazi SS concentration camp commandant
- Karl Svoboda (1929–2022), Austrian politician
- Karl O. Thomas (born 1963), United States Navy vice admiral
- Karl Urban (born 1972), New Zealand actor
- Karl Virtanen (born 1971), Sweden-Finnish journalist
- Karl Edward Wagner (1945–1994), American writer, editor and publisher
- Karl Wallenda (1905–1978), German-born tightrope artist
- Karl Weierstrass (1815–1897), German mathematician
- Karl Wendlinger (born 1968), Austrian race car driver
- Karl Williams (born 1971), American football player
- Karl Michael Ziehrer (1843–1922), Austrian composer
- Karl the Giant, a character from the 2003 film Big Fish
- Karl C. Agathon, a character in the re-imagined Battlestar Galactica series
- Karl Childers, protagonist in the 1996 film Sling Blade
- Karl Haulzemoff, a character in the 2011 film Cars 2
- Karl Hootkin, a character in the 2012 film Big Miracle
- Karl Mayer, divorce attorney and ex-husband of Susan Mayer on Desperate Housewives
- Karl Morgenthau, the first Marvel Comics supervillain known as Flag-Smasher
- Karl Stromberg, the main antagonist in the 1977 James Bond film The Spy Who Loved Me
- Karl Tanner, a character in the TV series Game of Thrones
- Karl Walken, fictional mayor in Black Cat magna series