The oldest elf in the Lord of the Rings universe is Galadriel, a powerful and wise elf who has lived for thousands of years. She was a member of the High Elves and was one of the first to travel to Middle-earth. She has seen the rise and fall of many civilizations and has been instrumental in many of the major events in the history of Middle-earth. She is a powerful and influential figure, and her wisdom and guidance are highly valued by many of the other characters in the story.