William Dazeley was born in Warwickshire and studied at Jesus College, Cambridge and the Guildhall School of Music and Drama.

His operatic roles have included Guglielmo (Cosi fan tutte), Anthony (Sweeney Todd), Figaro (Il Barbiere di Siviglia) with the Royal Opera House and Covent Garden; Owen Wingrave (Owen Wingrave) with Glyndebourne Touring Opera; Don Giovanni (Don Giovanni) with Deutsche Oper, Berlin; Dr Faust with Salzburg Festival and Theatre du Châtelet; Zurga (The Pearl Fishers) with San Francisco Opera; Ferryman (Curlew River) with Edinburgh Festival, Papageno (The Magic Flute) with English National Opera, Count (Le Nozze di Figaro) with Welsh National Opera, Maximilian (Candide) with Teatro di San Carlo, Naples; Eugene Onegin (Eugene Onegin) with New Zealand Opera; Posa (Don Carlos), Yeletsky (Queen of Spades), Don Giovanni and Mr Gedge (Albert Herring) with Opera North); Eisenstein (Die Fledermaus) with the Bolshoi, Moscow; Marcello (La Bohème) with Hamburg State Opera; Father (Hansel und Gretel) with Glyndebourne Festival Opera and Garsington Opera; and Captain von Trapp (The Sound of Music) at the Châtelet.

William appears frequently in concert alongside renowned orchestras and conductors, including the CBSO, Berlin Philharmonic, BBC Symphony, Philippe Herreweghe, John Eliot Gardiner and Leonard Slatkin. He performed the world premiere of songs by Harrison Birtwistle for the BBC Proms, and has recently performed Carmina Burana with Sydney Symphony Orchestra and L’Enfance du Christ with the Bayerische Rundfunk Munich. He has given recitals at the Wigmore Hall, Purcell Room, and St George’s Bristol, and is regularly invited to sing at Cheltenham, Aix en Provence and Saintes Festivals with such noted accompanists as Graham Johnson, Iain Burnside, Sholto Kynoch and Malcolm Martineau.