Olivia de Havilland has had a long history at the Oscars.  She received 5 Oscar nominations and was awarded the Best Actress Oscar twice. Additionally, she has presented at the Oscars, including most recently ,in 2003, at the 75th Annual Academy Awards.  Ms. De Havilland is a current member of the Academy and is eligible to cast votes for the Academy Awards. 

Olivia de Havilland as Melanie Hamilton Wilkes
"Gone With the Wind"
1939

Olivia de Havilland won the role of Melanie Wilkes in Gone With the Wind in 1939.  She gave a phenomenal performance and truly made the role her own.  She and Hattie McDaniel were both nominated for Best Supporting Actress in 1939 for their performances.  Ms. McDaniel edged out Olivia de Havilland for the Oscar.  It was widely reported that Olivia cried at the ceremony for not receiving the award but later acknowledged how wonderful it was that Hattie McDaniel had won the award and that she had been there to witness the event.