Nikolaus Harnoncourt (Nikolaus Count de la Fontaine und d'Harnoncourt-Unverzagt, (6 December 1929 – 5 March 2016) was an Austrian conductor, particularly known for his historically informed performances of music from the Classical era and earlier. Starting out as a classical cellist, he founded his own period instrument ensemble, Concentus Musicus Wien, in the 1950s, and became a pioneer of the Early Music movement. Around 1970, Harnoncourt started to conduct opera and concert performances, soon leading renowned international symphony orchestras, and appearing at leading concert halls, operatic venues and festivals. His repertoire has since widened to include composers of the 19th and 20th centuries. In 2001 and 2003, he conducted the Vienna New Year's Concert. Harnoncourt was also the author of several books, mostly on subjects of performance history and musical aesthetics.
Harnoncourt was born in Berlin, Germany. He was raised in Graz, Austria, and studied music in Vienna. His mother, Ladislaja Gräfin von Meran, Freiin von Brandhoven, was the granddaughter of the Habsburg Archduke Johann, the 13th child of the Emperor Leopold II. He is thus descended from various Holy Roman Emperors and other European royalty. His father, Eberhard de la Fontaine Graf d'Harnoncourt-Unverzagt, was an engineer working in Berlin who had two children from a previous marriage. Two years after Nikolaus's birth, his brother Philipp was born. The family eventually moved to Graz, where Eberhard had obtained a post in the state-government (Landesregierung) of Styria.
Harnoncourt was a cellist with the Vienna Symphony from 1952 to 1969. In 1953, he founded the period-instrument ensemble Concentus Musicus Wien with his wife, Alice Hoffelner. The Concentus Musicus Wien is dedicated to performances on period instruments, and by the 1970s his work with it had made him quite well known. He played the viola da gamba at this time, as well as the cello. For the Telefunken (later Teldec) label, Harnoncourt recorded a wide variety of the Baroque repertoire, beginning with the viol music of Henry Purcell, and extending to works including Johann Sebastian Bach's The Musical Offering, Claudio Monteverdi's L'incoronazione di Poppea, and Jean-Philippe Rameau's Castor et Pollux.
One reason that Harnoncourt left the Vienna Symphony was to become a conductor. He made his conducting debut at La Scala, Milan, in 1970, in a production of Monteverdi's Il ritorno d'Ulisse in patria.
In 1971, Harnoncourt started a joint project with conductor Gustav Leonhardt to record all of J.S. Bach's cantatas. The Teldec Bach cantata project was eventually completed in 1990, and was the only cantata cycle to utilise an all-male choir and soloist roster, with the exception of cantatas, nos. 51 and 199), which were intended for the female soprano voice. In 2001 a critically acclaimed and Grammy Award winning recording of Bach's St Matthew Passion conducted by Harnoncourt was released, which included the entire score of the piece in Bach's own hand on a CD-ROM (this is his third recording of the work).
Harnoncourt subsequently performed with many other orchestras using modern instruments, but still with an eye on historical authenticity in terms of tempi and dynamics, among other things. He also expanded his repertoire, continuing to play the baroque works which had given him prominence, but also championing the Viennese operetta repertoire. In recent years, he has made a benchmark recording of the Beethoven symphonies with the Chamber Orchestra of Europe (COE), and recorded the Beethoven piano concerti with Pierre-Laurent Aimard and the COE.
In addition, Harnoncourt is a guest conductor of the Vienna Philharmonic and has made several recordings with the orchestra.
 Between 1987 and 1991, he conducted four new productions of Mozart operas at the Vienna State Opera (1987-91: Idomeneo; 1988-90: Die Zauberflöte; 1989: Die Entführung aus dem Serail; 1989-91: Così fan tutte). He directed the Vienna Philharmonic's New Year's Day concerts in 2001 and 2003.
In 1992, Harnoncourt debuted at the Salzburg Festival conducting a concert with the Chamber Orchestra of Europe. In the following years, he led several concerts with the Chamber Orchestra of Europe, the Vienna Philharmonic and the Concentus Musicus. Harnoncourt also served as the conductor for major opera productions of the Festival: L'incoronazione di Poppea (1993), Le nozze di Figaro (1995 and 2006), Don Giovanni (2002, marking also Anna Netrebko's international breakthrough as Donna Anna, and 2003), La clemenza di Tito (2003 and 2006), King Arthur (2004). In 2012, Harnoncourt is scheduled to conduct a new Magic Flute, staged by Tobias Moretti.
In 2002 he recorded Anton Bruckner's Symphony No. 9 with the Vienna Philharmonic, with an accompanying second CD containing a lecture by Harnoncourt about the symphony with musical examples, including the rarely heard fragments from the unfinished finale.
Harnoncourt made his guest-conducting debut with the Concertgebouw Orchestra, Amsterdam, in 1975. He has continued as a guest conductor with the orchestra, including in several opera productions and recordings. In October 2000, the Royal Concertgebouw Orchestra named him their Honorair gastdirigent (Honorary Guest Conductor).
In 2009, Harnoncourt recorded Porgy and Bess by George Gershwin.
On December 5, 2015, one day before his 86th birthday, Harnoncourt announced his retirement. “My bodily strength requires me to cancel my future plans,” the Austrian said in a hand-written farewell letter to the audience of the hallowed Musikverein concert hall in Vienna.
Harnoncourt and his wife Alice have four children. Their daughter is the mezzo-soprano Elisabeth von Magnus. Their two surviving sons are Philipp and Franz. Their third son Eberhard, a violin maker, died in 1990 in an automobile accident.
Harnoncourt died on March 5, 2016.
- Erasmus Prize (Praemium Erasmianum Foundation, Netherlands, 1980)
- Joseph Marx Music Prize of the Province of Styria (1982)
- Austrian Cross of Honour for Science and Art, 1st class (1987)
- Honorary Membership of the Society of Music Friends in Vienna (1992)
- Léonie Sonning Music Prize (Denmark, 1993)
- Polar Music Prize (Sweden, 1994)
- Honorary Membership of the University of the Arts Graz (1995)
- Robert Schumann Prize (1997)
- Hans von Bülow Medal (1999, Berlin)
- Honorary Guest Conductor of the Royal Concertgebouw Orchestra (Amsterdam, 2000)
- Grammy Award (2001)
- Ernst von Siemens Music Prize (Bavarian Academy of Fine Arts, 2002)
- Bremen Music Festival Prize (2002)
- Georg Philipp Telemann Prize (Magdeburg, 2004)
- Kyoto Prize for Lifetime Achievement (Japan, 2005)
- Grand Gold Decoration with Star of Styria (2005)
- Leipzig Bach medal (Leipzig, 2007)
- Austrian Decoration for Science and Art (2008)
- Honorary doctor (Mozarteum University of Salzburg, 2008)
- Honorary Citizenship of Sankt Georgen im Attergau (2009)
- Gramophone Lifetime Achievement Award (London, 2009)
- Honorary Doctorate from the University of Music and Dance Cologne (2011)
- Gold Medal for services to the city of Vienna (2011)
- Romano Guardini Prize (2012)
- Voted into the Gramophone Hall of Fame (London, 2012)
Nikolaus Harnoncourt was a member of the Royal Swedish Academy of Music, Honorary Doctor of the University of Edinburgh and of the Order Pour le Mérite for Science and Art.