|Birth:||June 13, 1986|
|First appearance:||Our Very First Show|
|Last appearance:||Michelle Rides Again (Part 2)|
|Education:||New York University|
In 1987, at the age of six months, the twins were cast in the role of Michelle. They began filming at nine months of age. In order to comply with child labor laws that set strict limits on how long a child actor may work, the sisters took turns playing the role. The Olsens continued to portray Michelle throughout the show's run. There were a few episodes where the twins appeared together: "The Seven-Month Itch", "Greek Week", "The Devil Made Me Do It", and "Michelle Rides Again".
When the series began, Mary-Kate was the calmer, less fussy baby, and because her sister was crying all the time, Mary-Kate had to play Michelle for most of the scenes in season one. By the age of six, the girls (because they are fraternal twins) started to look so different that audiences could tell them apart. The producers considered to chose one twin over the other, and decided to have just Mary-Kate play the role. However, their fan base at the time was so huge, and co-star John Stamos did not want one twin to leave the show, so both girls were kept on. Mary-Kate would play the more tomboyish, athletic side of Michelle. She also generally has a better sense of humor than Ashley.
In 1998, three years after Full House's cancellation, she played Mary-Kate Burke on the one-season-long ABC sitcom Two of a Kind, from the same producers of Full House.
In 2015, she married French banker Olivier Sarkozy, brother of former French president, Nicolas Sarkozy.
- The Olsens became the youngest self-made millionaires in American history before they were 10 years old
- At age 6, they became the youngest producers in history
- Height: 4' 11¾" (1.52 m)
- She is left-handed, has round ears, and a freckle on her right cheek
- Has two horses and has won several horseback-riding prizes with them; rode her first horse during the making of To Grandmother's House We Go (1992)