Alyattes (Lydian language: 𐤥𐤠𐤩𐤥𐤤𐤯𐤤𐤮 Walweteś; Ancient Greek: Ἀλυάττης Aluáttēs; reigned c. 635 – c. 585 BC), sometimes described as Alyattes I, was the fourth king of the Mermnad dynasty in Lydia, the son of Sadyattes, grandson of Ardys, and great-grandson of Gyges. He died after a reign of 57 years and was succeeded by his son Croesus.
Alyattes was the first monarch who issued coins, made from electrum (and his successor Croesus was the first to issue gold coins). Alyattes is therefore sometimes mentioned as the originator of coinage, or of currency.