Mireille Delcroix is a French actress who has worked extensively in the field of dubbing, providing French voices for numerous actresses in film and television. She trained at the Conservatoire national supérieur d'art dramatique in Paris. Her career has included stage, film, and television acting, but she is best known for her prolific voice work. In dubbing, she is notably the regular French voice of English actress Maggie Smith, taking over the role of Minerva McGonagall in the Harry Potter film series starting with Harry Potter and the Half-Blood Prince in 2009. She has since voiced Maggie Smith in multiple films including Harry Potter and the Deathly Hallows – Part 2, Quartet, The Lady in the Van, and the Downton Abbey films, as well as the television series Downton Abbey. Among her extensive list of dubbing credits, she provides the voice of Doctor Grasnik, played by Jane Alexander, in the French version of the 2002 film The Ring. Other major voice roles include voicing Rose Henderson in Lost: Les Disparus, Granny in Once Upon a Time, and Nell O'Brien in Chesapeake Shores. She has also voiced actresses including L. Scott Caldwell, Kathy Baker, Diane Ladd, and Jane Alexander across various series. Her dubbing work in animation includes providing voices for the French versions of Nausicaä of the Valley of the Wind and the series Zoé Kézako.