Klaus Sperber (January 24, 1944 – August 6, 1983), known professionally as Klaus Nomi, was a German countertenor and baritone noted for his wide vocal range and an unusual, otherworldly stage persona.

In the 1970s, Nomi immersed himself in the East Village art scene. He was known for his bizarre and visionary theatrical live performances, heavy make-up, unusual costumes, and a highly stylized signature hairdo that flaunted a receding hairline. His songs were equally unusual, ranging from synthesizer-laden interpretations of classical opera to post-punk covers of 1960s pop standards like Chubby Checker's "The Twist" and Lou Christie's "Lightnin' Strikes". Nomi was one of David Bowie's backing singers for a 1979 performance on Saturday Night Live.

Klaus Nomi was born Klaus Sperber in Immenstadt, Bavaria, on January 24, 1944. He was raised by his single mother, Bettina Sperber, who had fled Essen, Rhine Province, for the Allgäu due to Allied bombing during World War II. His father was a soldier in the German Army with whom Bettina had a brief relationship during his furlough; he died from influenza before Nomi's birth. At age four, he and his mother moved back to the Ruhr, first to Fröndenberg before returning to Essen. Nomi grew up listening to classical music, gaining an interest in opera from listening to soprano Maria Callas over the radio, but also became fascinated with pop rock, buying Elvis Presley records with money he stole from his mother. Inspired by Callas, he developed a six octave vocal range and in the mid-1960s, he moved to West Berlin to study at Berlin University of the Arts, but as the school did not offer countertenor courses at the time, he trained to be a baritone. As he did not believe that earning a living on a musical career alone was feasible, Nomi took an apprenticeship as a pastry chef and worked as an usher at the Deutsche Oper, where he sang for the other ushers and maintenance crew on stage in front of the fire curtain after performances. He also sang opera arias at the Berlin gay discothèque Kleist-Kasino [de], under the stage name "Renata Castrata".

Nomi emigrated to New York City in 1972. He appeared in some off-Broadway theater work and operated a pastry shop as a day job. In 1977, Nomi appeared in a satirical camp production of Richard Wagner's Das Rheingold at Charles Ludlam's Ridiculous Theater Company as the Rheinmaidens and the Wood Bird. In October 1978, he took the artistic name "NOMI", initially as a mononym before rendering it as "Nomi" and adopting it as a last name. It stood as an anagram for "omni" ("all" or "every"), after the then-newly released science fiction magazine Omni.

Nomi came to the attention of the East Village art scene on November 2, 1978 with his performance in "New Wave Vaudeville", a four-night event at Irving Plaza MC'd by artist David McDermott. Dressed in a skin-tight spacesuit with a clear plastic cape, Nomi sang the aria "Mon cœur s'ouvre à ta voix" ("My heart opens to your voice") from Camille Saint-Saëns' opera Samson et Dalila. The performance ended with a chaotic crash of strobe lights, smoke bombs, and loud electronic sound effects as Nomi backed away into the smoke. Joey Arias recalled: "I still get goose pimples when I think about it ... It was like he was from a different planet and his parents were calling him home. When the smoke cleared, he was gone." After that performance Nomi was invited to perform at clubs all over New York City.

At the New Wave Vaudeville show Nomi met Kristian Hoffman, a songwriter for the Mumps. Hoffman was a performer and MC in the second incarnation of New Wave Vaudeville and a close friend of Susan Hannaford and Tom Scully, who produced the show, and Ann Magnuson, who directed it. Anya Phillips, then manager of James Chance and the Contortions, suggested Nomi and Hoffman form a band. Hoffman became Nomi's de facto musical director, assembling a band that included Page Wood from another New Wave vaudeville act, Come On, and Joe Katz, who was concurrently in The Student Teachers, the Accidents, and The Mumps.

Hoffman helped Nomi choose his pop covers, including the Lou Christie song "Lightnin' Strikes". Hoffman wrote several pop songs with which Nomi is closely identified: "The Nomi Song", "Total Eclipse", "After The Fall", and "Simple Man", the title song of Nomi's second RCA French LP. This configuration of the Klaus Nomi band performed at Manhattan clubs, including several performances at Max's Kansas City, Danceteria, Hurrah and the Mudd Club. He also appeared on Manhattan Cable's TV Party.

Disagreements with the management Nomi engaged led to the dissolution of this band, and Nomi continued without them. In the late 1970s, while performing at Club 57, The Mudd Club, the Pyramid Club, and other venues, Nomi assembled various up-and-coming models, singers, artists, and musicians to perform live with him, including Joey Arias, Keith Haring, John Sex and Kenny Scharf. He was briefly involved with Jean-Michel Basquiat, then known for his graffiti art as SAMO.