The mythical creature in Mesopotamian myth that stole the Tablets of Destiny was Anzu.
Anzu, also called Anzû or Imdugud, was a divine storm bird associated with thunderclouds and the southern wind. Mesopotamian art often represents him as a huge eagle with a lion’s head, combining the eagle’s power in the sky with the lion’s ferocity.
In the Epic of Anzu, the creature steals the Tablet of Destinies from Enlil’s sanctuary and hides it on a mountain. Possession of the tablet gives its holder authority over the fates and cosmic order. The gods fear Anzu and seek a champion to recover it. In the Old Babylonian version, the hero is Ningirsu; in the later Standard Babylonian version, the hero is Ninurta. Some traditions instead name Marduk as Anzu’s slayer.
A common mix-up is treating Anzu as simply an eagle. He is more specifically a storm-associated divine monster, and his name appears in both Sumerian and Akkadian traditions. The “Tablet of Destinies” is also singular in many translations, although references may use plural wording.