Caroline Gilchrist Rhea (born April 13, 1964) is a Canadian stand-up comedian and actress who voices Linda Flynn on Phineas and Ferb. She was also the original host of the reality show The Biggest Loser on NBC, until Alison Sweeney took her place after the end of the third season. She is also known for her role as Hilda Spellman on Sabrina the Teenage Witch, and for replacing Rosie O'Donnell as the hostess of her syndicated talk show, renamed The Caroline Rhea Show.