Destroyer

The Destroyer was an automated weapon used to guard the Weapon's Vault of Asgard. The Destroyer obeys the king of Asgard which at he time when Loki was king, went to Earth and went to kill Thor, Sif and the Warriors Three.

Thor
The Destroyer killed three Frost Giants when Odin gave a signal which interuped a ceremony for Thor to be king of Asgard. When Loki was king, the Destroyer was sent to kill Thor, Sif and the Warriors Three.