Charles Klein (January 7, 1867 - May 7, 1915) was an English-born playwright and actor who emigrated to America in 1883. Among his works was the libretto of John Philip Sousa's operetta, El Capitan. Klein's talented siblings included the composer Manuel and the critic Herman Klein. He drowned during the sinking of the RMS Lusitania. Klein's melodramas were among the most successful of the first decade of the twentieth century, primarily because of their focus on themes of contemporary life in the United States. In The Auctioneer (1901) and The Music Master (1904), actor David Warfield had great successes. Klein's best-regarded drama, The Lion and the Mouse (1905), was prompted by a visit to the US. Senate.