Mary-Kate Olsen and Ashley Olsen used to be child actresses.
Mary-Kate Olsen and Ashley Olsen ( born June 13 , 1986 ) , also known as the Olsen twins collectively , are American fashion designers and former child actresses . The fraternal twins made their acting debut as infants playing Michelle Tanner on the television series Full House . At the age of six , Mary-Kate and Ashley Olsen began starring together in TV , film , and video projects , which continued to their teenage years .