LOTR: Who is the Oldest Creature in Middle Earth?

The lore of Middle-earth extends far past the bounds of what’s explored in The Lord of the Rings. Tolkien had a whole host of extended stories about the universe he had created, including its origins and a lot of information about the beings and creatures that were there from the very beginning. There are multiple characters encountered during the story that have been in Middle-earth for an incredibly long time, and some that have lived a long life even before Arda and Middle-earth themselves were created.