Domenico Salvatori (27 September 1855 – 11 December 1909) along with Alessandro Moreschi, Domenico Mustafà and Giovanni Cesari, was one of the famous castrati singers of the late 19th century.
A boy soprano is a young male singer with an unchanged voice in the soprano range.
Soprano sfogato ("Vented" soprano) is a term which, in the art of singing, designates a contralto or mezzo-soprano who is capable—by sheer industry or natural talent—of extending their upper range and being able to encompass the coloratura soprano tessitura.
 An upwardly extended "natural" soprano is sometimes called "soprano assoluto."
A countertenor (or contra tenor) is a type of classical male singing voice whose vocal range is equivalent to that of the female contralto or mezzo-soprano voice types, generally extending from around G to D or E, although a sopranist (a specific kind of countertenor) may match the soprano's range of around C to C. Countertenors often are baritones or tenors at core, but rarely use this vocal range in performance.
A mezzo-soprano or mezzo ( , ; ] meaning "half soprano") is a type of classical female singing voice whose vocal range lies between the soprano and the contralto voice types.
 The mezzo-soprano's vocal range usually extends from the A below middle C to the A two octaves above (i.e. A–A in scientific pitch notation, where middle C = C).
 In the lower and upper extremes, some mezzo-sopranos may extend down to the F below middle C (F) and as high as "high C" (C).
Karin Branzell (24 September 189115 December 1974) was a Swedish operatic contralto (sometimes described as a mezzo-soprano), who had a prominent career at the Metropolitan Opera, New York, and in Europe.
 Her very wide range enabled her to sing both contralto roles and the occasional soprano role.
 She was particularly noted for her singing of the music of Richard Wagner, in roles such as Ortrud ("Lohengrin"), Venus ("Tannhäuser"), Erda ("Das Rheingold" and "Siegfried"), Brangäne ("Tristan und Isolde"), and Brunnhilde ("Die Walküre").
 She was considered on a par with Margarete Klose and Kerstin Thorborg as a Wagnerian contralto.
 Amneris ("Aida"), Dalila ("Samson et Dalila"), Herodias ("Salome"), and Clytemnestra ("Elektra") were among her other renowned roles.
A castrato (Italian, plural: "castrati") is a type of classical male singing voice equivalent to that of a soprano, mezzo-soprano, or contralto.
 The voice is produced by castration of the singer before puberty, or it occurs in one who, due to an endocrinological condition, never reaches sexual maturity.
A sopranist (also, sopranista or male soprano) is a male singer who is able to sing in the vocal tessitura of a soprano usually through the use of falsetto vocal production.
 This voice type is a specific kind of countertenor.
 In rare cases an adult man may be able to sing in the soprano range using his normal or modal voice and not falsetto due to endocrinological reasons, like Radu Marian, or as a result of a larynx that has not completely developed as in the case of Michael Maniaci.
Voice portals are the voice equivalent of web portals, giving access to information through spoken commands and voice responses.
 Ideally a voice portal could be an access point for any type of information, services, or transactions found on the Internet.
 Common uses include movie time listings and stock trading.
Karel Gott (born 14 July 1939, in Plzeň) is a Czech singer, and an amateur painter.
 He is considered the most successful male singer in the former Czechoslovakia and the Czech Republic, and has been voted the country's best male singer in the annual "Český slavík" (Czech Nightingale) national poll 41 times, most recently in 2016.
 He has also achieved considerable success in the German-speaking countries, where he is known as "the Golden Voice of Prague", winning the Goldene Stimmgabel award three times (1982, 1984, and 1995).
 Over the course of his career he has released over 100 albums and 100 compilation albums, and has sold an estimated 50–100 million records worldwide, 23 million of them in the German-speaking market, and about 15 million in Czechoslovakia and its successor states (Czech Republic and Slovakia).

Question: Who is a famous male singer with a voice equivalent to that of a soprano, mezzo-soprano, or contralto?
Answer: Domenico Salvatori