Destroyer

"The Jotuns must pay for what they have done!" "They have paid, with their lives. The Destroyer did its work, the Casket is safe, and all is well."

- Thor and Odin

The Destroyer (a.k.a. The Destroyer Automaton) was an enchanted Asgardian automaton used primarily to guard the Weapon's Vault of Asgard, though it could also be used as a weapon against its master's enemies. The Destroyer unquestionably obeyed the ruler of Asgard and wielder of Gungnir, no matter who the ruler may be at any given time. Thus, the Destroyer could be used both for good and evil intentions.

Serving Asgard's King
The Destroyer killed three Frost Giants inside Odin's Vault, when Odin gave a signal which interrupted a ceremony for Thor to be king of Asgard. When Loki usurped the throne of Asgard he took control of the Destroyer and sent it to kill his brother Thor.

Battle of Puente Antiguo
"Is that one of Stark's?" "I don't know. Guy never tells me anything."

- Jasper Sitwell and Phil Coulson

The Destroyer was sent through the Bifrost Bridge from Asgard to Earth; S.H.I.E.L.D. agents including Phil Coulson and Jasper Sitwell tried to deal with the situation but were quickly attacked by the Destroyer.

Temporarily waylaid by Lady Sif and the Warriors Three, it continued its advance through the New Mexico town of Puente Antiguo until Thor stepped forward to face it alone. Thor appealed to Loki through the Destroyer, asking Loki to take his life, but leave the nearby populace alone. The Destroyer then dealt him a mortal blow, but Thor's act of self-sacrifice caused his lost power to be restored, and with it he turned the suit's power in on itself, damaging it beyond its ability to function.

Under S.H.I.E.L.D.'s Jurisdiction
"That's excellent work Doctor. Now I need you to dismantle that thing and make it a hundred times smaller. And put a trigger on it!"

- Phil Coulson

The Destroyer was later confiscated by the agents of S.H.I.E.L.D. and taken to the S.H.I.E.L.D. Headquarters in New York City. A year after the battle of Puente Antiguo, S.H.I.E.L.D. scientists successfully reactivated the giant automaton.

A weapon which could shoot energy blasts similar to those of the Destroyer was soon made. That weapon was later used by Phil Coulson against Loki.

Capabilities
Centuries old, the Destroyer functions like a robot yet does not have the technological features to function as so. Nonetheless, it was built to protect the artifacts of Odin's Vault, defend Asgard, and, when ordered, relentlessly pursue and destroy any target it is set upon. The Destroyer operates at the behest of whoever holds Gungnir, the Asgardian ruler's spear, and can therefore be used for good or for evil depending on who sits on the throne. It can also therefore be stopped by an attack on its vulnerable master. The Destroyer was designed solely for battle and destruction.

Powers

 * Superhuman Strength: The Destroyer's large size and construction gives it formidable physical power, enough to bat away a car hurled at it, and send Volstagg flying with apparent ease. The Destroyer's immense superhuman strength enables it to effortlessly kill a being of human strength and resilience with as little as a back handed strike with an open hand. This allowed it to fatally injure a mortal Thor with severe blunt trauma which sent him flying through the air. With more effort, it can kill a Frost Giant or even Asgardian with its strength, as even the combined efforts of Lady Sif and the Warriors Three did not stand a chance against the Destroyer. Only Thor was able to hold his own against it, after fully regaining his powers.
 * Superhuman Durability: The Destroyer is constructed of other worldly materials that make it highly resistant to damage. Even when pierced by Sif's Asgardian lance, it was able to continue functioning. Also, no known human weaponry can harm or destroy it, with Mjølnir being the only known weapon capable of harming it.
 * Odinforce Blast: The Destroyer powered by the Odinforce,which resembles a fiery energy,  can be unleashed through an aperture in its head. When it does this, part of the facial structure retracts downward into the lower face and the energy discharge lances out in a wide, orange-white, fire like beam. This beam is extremely powerful, as the touch of it is enough to blast a car to pieces, vaporize a living being (even one as durable as a Frost Giant) or lay waste to any structure (a building, for example) it lays its "eyes" upon. Only beings of incredible power, like Thor, are able to withstand these blasts.
 * Retrograde Positioning: The Destroyer is able to rearrange the armor pieces that make up its body, giving it a nearly unlimited range of motion. When attacked from behind it was able to face its opponent without turning around by instead fully rotating its arms, legs, and head. This was used when Sif drove a lance through its back and the Destroyer swiftly re-positions itself to blast her.
 * Sensory Scrying and Partial Possession: The Destroyer is linked to whoever holds Gungnir and recognizes the spear's wielder as its master. The wielder of Gungnir can perceive whatever transpires around the armor and pilot it by partially possessing it, even if they are separated at vast distances across the Nine Realms. Thus, it was first commanded by Odin, and then by Loki. Odin seemed to be able use it to Frost Giants breaking into his vault, and that Loki was using it to try and kill Thor while he was in Odinsleep.

Weaknesses

 * Wielder of Gungnir: The Destroyer operates at the behest of whoever holds Gungnir, the Asgardian ruler's spear, and can therefore be used for good or for evil, depending on who sits on the throne of Asgard. Thus, it can be stopped by an attack on its master, should they have left themselves vulnerable to attack.
 * Weapons of Great Power: The Destroyer can also be defeated through the use of another extremely powerful enchanted weapon, like Mjølnir, which Thor used to defeat and destroy it.

Trivia

 * In the comics, the Destroyer was built by Odin as a weapon to use against the Celestials.