Iestyn Davies, MBE (born 16 September 1979) is a British classical countertenor.

Davies was born in York, England and first studied piano and recorder, mentored in his early years by his father Ioan. From the age of eight he sang as a boy treble in the choir of St John's College, Cambridge. He began singing countertenor in his teens, at Wells Cathedral School. He returned to St John's as a choral scholar, graduating in archaeology and anthropology. He gained his DipRAM from, and was later appointed ARAM by, the Royal Academy of Music.^[ In 2004 he won the Audience Prize at the London Handel Singing Competition and in 2010 was named "Young Artist of the Year" by the Royal Philharmonic Society.
Davies' father Ioan was a long-standing cellist with the Fitzwilliam Quartet and a member of St. John's College

Davies's opera career to date has included the role of Ottone in Monteverdi's L'incoronazione di Poppea for both Zürich Opera and Glyndebourne Festival Opera, and in Handel's Partenopehe has sung Arsace for New York City Opera and Armindo for English National Opera. He has sung Oberon in Britten's A Midsummer Night's Dream for Houston Grand Opera, Apollo in Britten's Death in Venice for English National Opera and Hamor in Handel's Jephtha for both Welsh National Opera and Opéra National de Bordeaux. In 2010 he sang Creonte in Agostino Steffani's Niobe at the Royal Opera House, Covent Garden. In 2011, he sang the part of Unulfo in Handel's Rodelinda at the Metropolitan Opera in New York.
He has appeared in concert at Teatro alla Scala with Gustavo Dudamel, at the Concertgebouw and the Tonhalle with Ton Koopman, at the Barbican, the Théâtre des Champs-Élysées and Lincoln Center, and at the Royal Albert Hall in the BBC Proms. He has worked with many leading orchestras including the Orchestra of the Age of Enlightenment, Academy of Ancient Music, Scottish Chamber Orchestra, the Hallé Orchestra, the King's Consort, Northern Sinfonia, the English Concert, the Akademie für Alte Musik, Berlin, Retrospect Ensemble, the Parley of Instruments, Il Complesso Barocco, the Gabrieli Consort and Players, the Minnesota Orchestra, London Philharmonic Orchestra, Britten Sinfonia, Concerto Köln, Concerto Copenhagen, Ensemble Matheus, Fretworkand the Bournemouth Symphony Orchestra.
Leading interpreters with whom Davies has collaborated include conductors Rinaldo Alessandrini, Philippe Bender, Harry Bicket, Ivor Bolton, Frans Brüggen, Harry Christophers, Stephen Cleobury, Laurence Cummings, Christian Curnyn, Alan Curtis, Steven Devine, Richard Egarr, John Eliot Gardiner, Edward Gardner, Jane Glover, Paul Goodwin, Emmanuelle Haïm, Matthew Halls, Nikolas Harnoncourt, Edward Higginbottom, David Hill, Benedict Hoffnung, Christopher Hogwood, Peter Holman, Robert King, Nicholas Kraemer, Stephen Layton, Iain Leddingham, Charles Mackerras, Paul McCreesh, Kenneth Montgomery, Lars Ulrik Mortensen, Kent Nagano, Donald Nally, James O'Donnell, Enrico Onofri, Daniel Reuss, Jeffrey Skidmore, Jean-Christophe Spinosi, Charles Stewart, Patrick Summers, Elizabeth Wallfisch, Alison Balsom and Dominic Wheeler, and recitalists Julius Drake, Mark Padmore, Philip Langridge and Roger Vignoles.
Davies was the guest soloist in Leonard Bernstein's 'Chichester Psalms' at the Last Night of the Proms at the Royal Albert Hall in September 2013.
Davies's engagements include a Carnegie Hall recital debut, his debut at the Metropolitan Opera to which he was re-invited for the 2012 and 2013 seasons, and his Chicago Lyric Opera debut. He sang his first full operatic performance for La Scala in Death in Venice. In London, he sang the role of Oberon in A Midsummer Night's Dream at English National Opera.
Beginning in December 2017, he performed the singing voice of Farinelli in Farinelli and the King at the Belasco Theatre on Broadway. The production will run for 16 weeks and will star Mark Rylance as King Philippe V of Spain. Davies is reprising the role he played at Shakespeare's Globe and in London's West End.