Gustav Leonhardt (born 30 May 1928, died 16 January 2012) was a highly acclaimed Dutch keyboard player, conductor, musicologist, teacher and editor. Leonhardt was a leader in the movement to perform music on period instruments. The keyboard instruments on which he performed and recorded include the harpsichord, pipe organ, claviorganum (a combination of a harpsichord and an organ), clavichord, and fortepiano.
From 1947 to 1950 Gustav Leonhardt studied organ and harpsichord with Eduard Müller at the Schola Cantorum Basiliensis in Basel. He made his debut as a harpsichordist in Vienna in 1950 and studied musicology there. He served as professor of harpsichord at the Academy of Music from 1952 to 1955 and as professor of harpsichord at the Amsterdam Conservatory from 1954. He was also a church organist.
Leonhardt made his first recordings of Johann Sebastian Bach's works for harpsichord in the early 1950s, including 1953 recordings of the Goldberg Variations and of the Art of Fugue. The latter embodies the thesis he had published the previous year arguing that the work was intended for the keyboard, a conclusion now widely accepted. The recordings helped establish his reputation as a fine harpsichordist and brilliant Bach interpreter. In 1954 he led the Leonhardt Baroque Ensemble with the great English counter-tenor Alfred Deller in a pioneering recording of two Bach cantatas. The Ensemble included his wife Marie Leonhardt, Eduard Melkus (violins), Alice Harnoncourt-Hoffelner (violin, viola), Nikolaus Harnoncourt (cello), and Michel Piguet (oboe).
Leonhardt performed and conducted a variety of solo, chamber, orchestral, operatic, and choral music from the Renaissance, Baroque and Classical periods. He and Harnoncourt undertook the project of recording the first complete cycle of Bach's cantatas on period instruments; the two conductors divided up the cantatas and recorded their assigned cantatas with their own ensembles. The undertaking took almost twenty years, from 1971 to 1990. Leonhardt has also recorded Bach's St Matthew Passion and Mass in B minor, and much other baroque choral music.
As a keyboardist, Leonhardt recorded much of the repertory from the Elizabethan William Byrd to some sonatas of Wolfgang Amadeus Mozart, with most of his focus on the Baroque era, including most of the French clavecinistes. He has recorded Bach's Goldberg Variations (three times), Partitas (twice), the Art of Fugue (twice), Well-Tempered Clavier, French Suites, English Suites, and many individual works for harpsichord, clavichord, and organ.
Leonhardt had a significant influence on the technique and style of many harpsichordists of the second half of the 20th century, through his recordings, editions, and teaching. His students include such harpsichordists as Bob van Asperen, Lisa Crawford, Christopher Hogwood, Philippe Herreweghe, Alan Curtis, Richard Egarr, John Gibbons, Pierre Hantaï, Ketil Haugsand, Ton Koopman, Charlotte Mattax, Davitt Moroney, Martin Pearlman (Music Director of Boston Baroque), Edward Parmentier, Christophe Rousset, Andreas Staier, Skip Sempé, Colin Tilney, Glen Wilson, and Jeannette Sorrell (founder of Apollo's Fire).
Leonhardt appeared in the role of J. S. Bach in The Chronicle of Anna Magdalena Bach, the 1968 film by Jean-Marie Straub and Danièle Huillet.
Since 1965 Leonhardt had been a member of the jury at the triennal international harpsichord concours in Bruges. He was the only jury member who had been in all sixteen jurys from 1965-2010.
Among the awards given to him were the Medal of Honour for the Arts and Sciences from the Netherlands, presented to him by Queen Beatrix in 2009, and the 1980 Erasmus Prize, which he shared with Harnoncourt; it honoured their recording of the complete Bach cantatas on the Teldec label. Leonhardt is doctor honoris causa of the universities of Dallas, Amsterdam, Harvard, Metz and Padua. In 2007 he was made Commander in the Crown Order in Belgium.