Hungarian-born American conductor known for his technical precision and control, both in symphonic music and in opera. He was especially known for his work with the Chicago Symphony Orchestra, of which he was music director from 1953 to 1962.

Reiner studied at the Budapest Royal Academy of Music, was associated with various small European opera houses, and (1914–21) was conductor of the Dresden Royal Opera. He went to the United States as principal conductor of the Cincinnati (Ohio) Symphony (1922–31) and from 1931 to 1941 was head of the opera and orchestral departments at the Curtis Institute of Music in Philadelphia.

Before going to Chicago he was music director of the Pittsburgh Symphony (1938–48) and of the Metropolitan Opera (1948–53) in New York City. Despite his despotic approach to orchestras, he was respected by orchestra members for his musicianship and mastery of conducting. He especially excelled in performances of works by German Classical and Romantic composers, notably Johannes Brahms and Richard Strauss.