This is an incomplete list of authors who have written libretti for operas. Only librettists with their own articles in Wikipedia are listed. The name of the composer of each opera is also given.
Giuseppe Adami (1878–1946)
Jules Adenis (1823–1900)
Franco Alfano (1875–1954)
Louis Anseaume (1721–1784)
George Antheil (1900–1959)
Guillaume Apollinaire (1880–1918)
W. H. Auden (1907–1973)
Ingeborg Bachmann (1926–1973)
Béla Balázs (1884–1949)
Luigi Balocchi (1766–1832)
Henri Auguste Barbier (1805–1882)
Jules Barbier (1825–1901)
Pierre Beaumarchais (1732–1799)
Vladimir Belsky (1866–1946)
Sem Benelli (1877–1949)
Hector Berlioz (1803–1869)
Giovanni Bertati (1735–1815)
Thomas Betterton (1635–1710)
Robin Blaser (born 1925)
Édouard Blau (1836–1906)
Arrigo Boito (1842–1918)
Jean-Nicolas Bouilly (1763–1842)
Bertolt Brecht (1898–1956)
Georg Büchner (1813–1837)
Francis Burnand (1836–1917)
Giovanni Francesco Busenello (1598–1659)
Ferruccio Busoni (1866–1924)
Massimo Cacciari (born 1944)
Louis de Cahusac (1706–1759)
Henri Caïn (1859–1937)
Italo Calvino (1923–1985)
Ranieri de' Calzabigi (1714–1795)
Salvadore Cammarano (1801–1852)
Michel Carré (1821–1872)
Nick Cave (born 1957)
Ernest Chausson (1855–1899)
Helmina von Chézy (1783–1856)
Henry Fothergill Chorley (1808–1872)
Guelfo Civinini (1873–1954)
Jean Cocteau (1889–1963)
J. M. Coetzee (born 1940)
Colette (1873–1954)
Marco Coltellini (1719–1777)
Jeremy Commons (born 1933)
William Congreve (1670–1729)
Eugène Cormon (1810–1903)
Thomas Corneille (1625–1709)
Hector-Jonathan Crémieux (1828–1892)
Michael Cristofer (born 1945)
Francis de Croisset (1877–1937)
Eric Crozier (1914–1994)
César Cui (1835–1918)
Gabriele D'Annunzio (1863–1938)
Lorenzo Da Ponte (1749–1838)
William Davenant (1606–1668)
Giovanni de Gamerra (1743–1803)
Constance DeJong (born 1950)
Frederick Delius (1862–1934)
Philippe Néricault Destouches (1680–1754)
Eduard Devrient (1801–1877)
Gaetano Donizetti (1797–1848)
John Dryden (1631–1700)
Gottfried von Einem (1918–1996)
Adolphe d'Ennery (1811–1899)
Victor Erofeyev (born 1947)
Hanns Heinz Ewers (1871–1943)
Mohammed Fairouz (born 1985)
Duncan Fallowell (born 1948)
Charles-Simon Favart (1710–1792)
Lorenzo Ferrero (born 1951)
Jacopo Ferretti (1784–1852)
Ferdinando Fontana (1850–1919)
E. M. Forster (1879–1970)
Giovacchino Forzano (1884–1970)
Frederick the Great (1712–1786)
Christopher Fry (1907–2005)
Kate Gale (born 1965)
Louis Gallet (1835–1898)
John Gay (1685–1732)
Richard Genée (1823–1895)
Ira Gershwin (1896–1983)
Antonio Ghislanzoni (1824–1893)
Giuseppe Giacosa (1847–1906) and Luigi Illica (1857–1919)
W. S. Gilbert (1836–1911)
Philippe Gille (1831–1901)
Alvise Giusti (1709–1766)
Nikolai Gogol (1809–1852)
Carlo Goldoni (1707–1793)
Edmond Gondinet (1828–1888)
Alice Goodman (born 1958)
Vincenzo Grimani (1652/1655–1710)
Sydney Grundy (1848–1914)
Nicolas-François Guillard (1752–1814)
Daron Hagen (born 1961)
Thomas Hales (c.1740–1780)
Ludovic Halévy (1834–1908)
Christopher Hampton (born 1946)
David Harsent (born 1942)
Georges Hartmann (1843–1900)
Nicola Francesco Haym (1678–1729)
Philip Hensher (born 1965)
DuBose Heyward (1885–1940)
Ernest Hilbert (born 1970)
Paul Hindemith (1895–1963)
Russell Hoban (born 1925)
Hugo von Hofmannsthal (1874–1925)
François-Benoît Hoffman (1760–1828)
Basil Hood (1864–1917)
Victor Hugo (1802–1885)
David Henry Hwang (born 1957)
Luigi Illica (1857–1919)
Jarosław Iwaszkiewicz (1894–1980)
Leoš Janáček (1854–1928)
Scott Joplin (1868–1917)
Étienne de Jouy (1764–1846)
Georg Kaiser (1878–1945)
Chester Kallman see Auden
Johann Friedrich Kind (1768–1843)
Kenneth Koch (1925–2002)
Eliška Krásnohorská (1847–1926)
Clemens Krauss (1893–1954)
Antoine Houdar de la Motte (1672–1731)
Ferdinand Lemaire (1832–1879)
Kasi Lemmons (born 1961)
Ruggero Leoncavallo (1857–1919)
Doris Lessing (1919–2013)
Amin Maalouf (born 1949)
Daniel MacIvor (born 1962)
Maurice Maeterlinck (1862–1949)
Andrea Maffei (1798–1885)
Albéric Magnard (1865–1914)
Jean-François Marmontel (1723–1799)
Henri Meilhac (1831–1897)
Anne-Honoré-Joseph Duveyrier de Mélesville (1787–1865)
Guido Menasci (1867–1925)
Catulle Mendès (1841–1909)
Gian Carlo Menotti (1911–2007)
Joseph Méry (1798–1866)
Olivier Messiaen (1908–1992)
Pietro Metastasio (1698–1782)
Madeleine Milhaud (1902–2008)
Nicolò Minato (ca. 1630–1698)
Paul Muldoon (born 1951)
Modest Mussorgsky (1839–1881)
Émile de Najac (1828–1899)
Charles Nuitter (1828–1899)
Meredith Oakes (born 1946)
Marc Okrand (born 1948)
Martin Opitz (1597–1639)
John Oxenford (1812–1877)
Francesco Maria Piave (1810–1876)
Arthur Wing Pinero (1855–1934)
Myfanwy Piper (1911–1997)
James Robinson Planché (1796–1880)
William Plomer (1903–1973)
David Pountney (born 1947)
Sergei Prokofiev (1891–1953)
Alexander Pushkin (1799–1837)
Philippe Quinault (1635–1688)
Jean Richepin (1849–1926)
Nikolai Rimsky-Korsakov (1844–1908)
Ottavio Rinuccini (1562–1621)
Michael Symmons Roberts (born 1963)
Felice Romani (1788–1865)
Giulio Rospigliosi (later Pope Clement IX) (1600–1669)
Gaetano Rossi (1774–1855)
Jean-Jacques Rousseau (1712–1778)
Pierre-Charles Roy (1683–1764)
Alphonse Royer (1803–1875)
Jules-Henri Vernoy de Saint-Georges (1799–1875)
Emanuel Schikaneder (1751–1812)
Arnold Schoenberg (1874–1951)
Eugène Scribe (1791–1861)
Michel-Jean Sedaine (1719–1797)
Peter Sellars (born 1957)
Elkanah Settle (1648–1724)
Thomas Shadwell (c. 1642–1692)
William Shakespeare (1564–1616)
Richard Brinsley Sheridan (1751–1816)
Renato Simoni (1875–1952)
Montagu Slater (1902–1956)
Temistocle Solera (1815–1878)
Antonio Somma (1809–1864)
Gertrude Stein (1874–1946)
B. C. Stephenson (1838–1906)
Cesare Sterbini (1784–1831)
Richard Strauss (1864–1949)
Igor Stravinsky (1882–1971)
Alessandro Striggio (1573–1630)
John Millington Synge (1871–1909)
Giovanni Targioni-Tozzetti (1863–1934)
Nahum Tate (1652–1715)
Modest Ilyich Tchaikovsky (1850–1916)
Emmanuel Théaulon (1787–1841)
Michael Tippett (1905–1998)
Andrea Leone Tottola (?–1831)
Étienne Tréfeu (1821–1903)
Albert Vanloo (1846–1920)
Giambattista Varesco (1735–1805)
Ralph Vaughan Williams (1872–1958)
Jules-Henri Vernoy de Saint-Georges (1799–1875) – see above under S
Voltaire (1694–1778)
Richard Wagner (1813–1883)
Camillo Walzel (1829–1895) pseudonym F Zell
Thornton Wilder (1897–1975)
Albert Willemetz (1887–1964)
Ernst von Wolzogen (1855–1934)
Arthur Yorinks (born 1953)
Carlo Zangarini (1873–1943)
Franco Zeffirelli (1923–2019)
Alexander von Zemlinsky (1871–1942)
Apostolo Zeno (1668–1750)
Julius Zeyer (1841–1901)
Bernd Alois Zimmermann (1918–1970)
Émile Zola (1840–1902)
Stefan Zweig (1881–1942)