Which beast was sent by the goddess Ishtar to punish Gilgamesh?

The beast sent by the goddess Ishtar to punish Gilgamesh was the Bull of Heaven.

In Tablet VI of the Standard Babylonian Epic of Gilgamesh, Ishtar becomes enraged after Gilgamesh rejects her advances and insults the disastrous fates of her former lovers. She goes to her father, the sky god Anu, and demands the Bull of Heaven so she can unleash it against Gilgamesh and the people of Uruk.

Anu warns that releasing the bull will bring devastation and seven years of famine, but Ishtar claims that she has stored enough grain for both humans and animals. Once released, the bull causes widespread destruction. Gilgamesh and his companion Enkidu eventually kill it together, and Enkidu throws its right thigh toward Ishtar in defiance.

The story exists in both Sumerian and Akkadian forms. In the earlier Sumerian version, Inanna—the Sumerian counterpart of Ishtar—sends the bull for reasons that are less clearly explained. The beast is also associated by some scholars with the constellation Taurus.