In J.R.R. Tolkien’s fictional history, Aulë was the Vala known as the Smith.
Aulë is one of the Valar, the powerful beings who help shape Arda. He is associated with craftsmanship, substances of the earth, metalworking, and the creation of physical things. Tolkien’s mythology presents him as a master maker whose desire to create leads to the secret making of the Dwarves.
According to The Silmarillion, Aulë creates the Dwarves before the awakening of the Elves. Ilúvatar ultimately adopts them into his design, allowing them to live, but Aulë must wait until the appointed time before they awaken.
Aulë is not the ruler of all the Valar. Manwë is associated with the airs and is their high king, Ulmo with the waters, and Oromë with forests and the hunt. Those roles make the Smith epithet specifically identifying Aulë.