Erich Kleiber (5 August 1890 – 27 January 1956) was an Austrian, later Argentine, conductor, known for his interpretations of the classics and as an advocate of new music.

Kleiber was born in Vienna, and after studying at the Prague Conservatory, he followed the traditional route for an aspiring conductor in German-speaking countries of the time, starting as a répétiteur in an opera house and moving into conducting in increasingly senior positions. After holding posts in Darmstadt (1912), Barmen-Elberfeld (1919), Düsseldorf (1921) and Mannheim (1922) he was appointed in 1923 to the important post of musical director of the Berlin State Opera.

In Berlin, Kleiber's scrupulous musicianship and enterprising programming won him a high reputation, but after the Nazi Party came to power in Germany in 1933, he resigned in protest against its oppressive policies, and left the country, basing himself and his family in Buenos Aires. For the rest of his career he was a freelance, guest conducting internationally in opera houses and concert halls. He played an important part in the creation of the Royal Opera in London, but a plan for him to return to the Berlin State Opera in the 1950s fell foul of politics.

Kleiber was regarded as an outstanding conductor of Mozart, Beethoven and Richard Strauss and encouraged modern composers, including Alban Berg, whose Wozzeck he premiered. He died suddenly in Zurich at the age of 65.