April 3 is a popular day for celebrity birthdays, but perhaps the most notable is that of acting and singing legend Doris Day, who turns 88 years old today.

Day holds the distinction of being the biggest female box-office star in history, according to NPR, having starred in such classics as Alfred Hitchcock's The Man Who Knew Too Much, Calamity Jane, Love Me or Leave Me, Pillow Talk, which earned her an Academy Award nomination, and dozens more.

Day stopped acting in 1968, after 20 years in Hollywood, in order to devote her time to animal welfare activism. To say happy birthday, Turner Classic Movies (TCM) has named Day as its Star of the Month for April, showcasing 28 of her films during prime time slots on the network. In addition, Warner Home Video released a new four-film box set of her works last month, and Sony debuts a double CD set featuring 31 of Day's classic songs today.

Day's persona as the original American sweetheart landed her roles in films with fellow acting giants Rock Hudson, Cary Grant and Jimmy Stewart. Day still works for the humane treatment of animals to this day, and just last year she released her latest album, My Heart, her first since 1967's The Love Album.