Mary-Kate and Ashley in Action! was an animated children's television series featuring the voices and likeness of Mary-Kate and Ashley Olsen. It is also a series of books that spun off, from the show. The show premiered on October 20, 2001, on the ABC block Disney's One Saturday Morning, and was cancelled after one season due to low ratings.

Mary-Kate Olsen and Ashley Fuller Olsen, also known as the Olsen twins, are American fashion designers and former actresses. Mary-Kate and Ashley made their acting debut as infants playing Michelle Tanner on the television sitcom Full House (1987–1995). As they grew older, they began starring in other television shows, films, and media through their own production company, Dualstar. The twins became preteen icons, and some of the wealthiest women in the entertainment industry at a young age.