Leviathans

Leviathans are alien beasts and warships for the Chitauri.

The Avengers
Leviathans are gargantuan beasts used by the Chitauri during their assault on Earth as both warships and assault crafts. The first Leviathan arrived on Earth is initially confronted by Iron Man, who makes it follow him to where the rest of his team is. Once here, he finds out that Bruce Banner has joined the Avengers: Banner, in the blink of an eye, transforms into the Hulk and destroys the Leviathan with a single punch.

Other Leviathans arrive from the dimensional portal and attack New York, but they're all defeated, mainly by Hulk, Thor and Iron Man. When Stark crosses the portal, he sees that there are many more Leviathans on the other side, ready to attack, but once the mother ship is destroyed, every Chitauri, Leviathans included, die.

Relationships

 * Thanos - Master
 * Loki Laufeyson - Commander
 * Chitauri - Passengers and allies.
 * The Avengers - Enemy.

Trivia

 * The "Leviathans" shares some similarities with the Midgard Serpent, a recurring villain in Thor comics, often at Loki's service.
 * The Leviathan is also the name of the HYDRA submarine in Captain America and Thor: Avengers!.
 * Levaithans are original creations by Zak Penn and Joss Whedon.