Rumer Willis celebrated her 21st birthday with an Elvis Presley impersonator on Saturday night. The "Sorority Row" star was serenaded by the performer at Tao restaurant and nightclub, where she recognized reaching the milestone age with around 55 friends and family, including parents Bruce Willis and Demi Moore, step-parents Ashton Kutcher and Emma Hemming, boyfriend Micah Alberti, sisters Tallulah, 18, and Scout, 15, and close pals Holly Madison and Audrina Partridge.