Leviathans are the zerg's equivalent of a capital ship. They are classified as class-10 zerg flyers and are the largest in terran records, even larger than a mothership, though dwarfed by an arkship, and have been referred to as "moon sized." Measurements taken by the Terran Dominion have placed the leviathan at being around 6.7 kilometers long. Leviathans possess interior evolution chambers, can store tens of thousands of zerg strains within their interior chambers, and are capable of deep-space travel and can land on planets. They can operate in temperature conditions of near absolute zero and are capable of traveling through warp space.Sacs may be dropped from leviathans. Because of the sheer size, wraith sensors are unable to penetrate deep enough to see the leviathans' interior spaces.
Leviathans are typically armed with a daunting array of bio-weapons. Giant, hollow tentacles resembling those of the spine crawler can grab smaller craft or puncture the hulls of larger ships and insert zerg boarding parties. Most leviathans can launch bile swarms at their enemies, and unleash powerful bio-plasmid charges that deal devastating damage to their targets. Furthermore, cocoons birthed within the leviathan are capable of mutating into mutalisks and brood lords.
Leviathans were once space-borne creatures before being infested by the zerg, turning them into armored carriers. They were used by the Swarm in war as early as the fall of Aiur, and at least one was present at Char in the Second Great War. During the Battle of Char, zerg broods in leviathans were on their way to the planet when Kerrigan was de-infested. These broods were then scattered or destroyed. Upon her return to the Swarm, Kerrigan's new base of operations was a leviathan. It would fly to different planets and land on them at her direction.
Leviathans create airborne eggs and cocoons to spawn mutalisks and brood lords, respectively. It attacks with the four spine crawlers on its underbelly and bile swarm projectiles, and launches scourges and bioplasmid globes dealing 500 damage. It may also put enemy units and buildings in biostasis, stunning them temporarily. It may be confronted by the player in the mission "Shatter the Sky" or later in "All In", depending on decisions made beforehand. When it dies, it loses its coloration before it explodes.
The best way to bring down leviathans is by massing marines and/or vikings.
In Heart of the Swarm, once Kerrigan has reached level 60 she can summon leviathans to the field, one at a time. These leviathans are smaller and do not spawn brood lords, scourges or mutalisks. They also only have 1000 hit points and last 4 minutes. Kerrigan has to wait 5 minutes before she can summon another one (4 minutes with ability efficiency). Notably, the leviathan can still attack while moving and attack both ground and air targets at the same time.
Brutalisks and Leviathans gain Symbiotes that follow them, attacking enemies and protecting their host with the Carapace ability.
Damage: 20 Mastery: +0.66 attack damage per Symbiote Ability Improvement mastery point. Up to a maximum 40 attack damage Cooldown: 1 Range: 6 Carapace ability: when the Ultimate Evolution is taking damage, Symbiotes create a Carapace that can absorb 200 damage. Mastery: +6.66 absorbed damage per Symbiote Ability Improvement mastery point. Up to a maximum of 400 absorbed damage Carapace duration: 8 Carapace cooldown: 20
The Leviathan is a large creature in the Bible (e.g. Job 3:18; 41:1). BDB translates leviathan as serpent or dragon. In Isaiah and the Psalms, "leviathan" can represent Egypt, the traditional nemesis of Israel. In Modern Hebrew, it simply means "Whale."
The unit description states that the leviathan spawns scourges and mutalisks; however, the game unit spawns mutalisks and brood lords instead.