In "The Lord of the Rings" film series, who portrayed Arwen Undómiel?

Didn't mention she's the daughter of Steven Tyler of Aerosmith

aqualung, But adopted by Todd Rundgren

I thought her Birthname was Olivia Tyler. her Birthname is Liv. Steven Tyler said he loved the name Olivia and that's what he named her, Liv was her Nick Name she goes by. People please get your Answers Straight.....

Steven is not relevant to Lord of the Rings but a friend of mine was his makeup artist