Arwen Undómiel was born to Elrond and Celebrían, in TA 241. She was the sister to Elladan and Elrohir. She was half-elven, and married Aragorn. She was so beautiful the elves said that she was the very likeness of Lúthien come on the earth again.

Arwen spent much of her early life in Lothlórien, the land of her mother's people. But in TA 2951, she met Aragorn in Rivendell when she came to visit her father. In TA 2980, Aragorn came to Lothlórien and there they met again, and decided that one day they would marry.

However, Elrond put a number of conditions in front of Arwen and Aragorn. He said to Aragorn that he would not let Arwen marry anyone less than the King of Gondor and Arnor, and he said that Arwen would enjoy the life of the elves as long as he was in Middle-earth. Arwen could therefore not choose a mortal life until her father sailed over the Sea.

She made the standard that was flown on one of the Corsair ships Aragorn commanded in the War of the Ring. She wrought the stars on the banner out of gems.

She and Aragorn wed on Midsummer's Day in TA 3019. As she was one of the half-elven, she chose to become a mortal when she wed Aragorn, and she gave her passage to the West to Frodo Baggins.

She bore Aragorn a son called Eldarion and a few daughters. When Aragorn died, she returned to Lothlórien and laid herself upon Cerin Amroth to die. There her grave will stay until the shape of the world is changed.