Herman Klein (born Hermann Klein; 23 July 1856 – 10 March 1934) was an English music critic, author and teacher of singing. Klein's famous brothers included Charles and Manuel Klein. His second wife was the writer Kathleen Clarice Louise Cornwell, and one of their children was the writer Denise Robins.
For thirteen years, Klein was a vocal teacher at the Guildhall School of Music in London, becoming a lifelong proponent of the methods of Manuel Garcia and helping to edit Garcia's book on the subject. In 1876 he took up musical journalism, writing for The Sunday Times from 1881–1901, among other publications. He also contributed prolifically to The Musical Times. From 1901 to 1909, Klein lived and taught singing in New York City, where he wrote for The New York Herald. He was one of the first critics to take notice of the gramophone and was appointed "musical adviser" to Columbia Records in 1906 in New York. He returned to England in 1909.
Klein wrote over half a dozen books about music and singers, as well as English translations of operas and art songs. He was a noted authority on Gilbert and Sullivan. In 1924 he began writing for The Gramophone and was in charge of operatic reviews, as well as contributing a monthly article on singing, from then until his death.