Overlord

The overlord was a Zerg flyer that provided control for the Swarm's lesser minions. Evolved from the Gargantis proximae, a species of giant, semi-intelligent, space-faring creatures, the overlord coordinated broods on behalf of the cerebrates, scouted with enhanced senses, and broadcast the psionic commands that bound the Swarm together. Of all Zerg breeds it was among the least altered from its source genus, a deliberate restraint that preserved both its extraordinary psionic capacity and, in some cases, the buried memories of the creatures it had once been. (StarCraft; Overlord (StarCraft II official site); Just an Overlord)

Origin#

Overlords were evolved from the Gargantis proximae, a species of giant, space-faring, and semi-intelligent creatures that volunteered to be assimilated in order to avoid extinction. According to the StarCraft manual, overlords were utilized by the Zerg before the Swarm left Zerus and were derived from this same genus. Once assimilated, they were put to work helping the cerebrates control and coordinate their broods and scouting with their enhanced senses. (StarCraft; Overlord (StarCraft II official site); Just an Overlord)

The Zerg altered the Gargantis far less than they did most assimilated species. Dr. Talen Ayers proposed two explanations. One was that the Gargantis already possessed the properties the Zerg desired, so little modification of their genetic code was needed. The other was that the Zerg were unwilling to meddle deeply with the structural makeup of a species that possessed great psionic ability, knowing that even the slightest change could destroy it. Ayers favored the second. As a result, the overlord's core genetic matrix is atypically homogeneous, over ninety percent unchanged, and the minimal alterations preserved the original creatures' memories. The most ancient overlords, essentially assimilated Gargantis, could regain their individuality upon becoming feral. (Project Blackstone; Overlord (StarCraft II official site))

Senses and psionic relay#

The elongated appendages that once hung from the underbellies of the Gargantis evolved into an array of microscopic filaments that gather sensory and spatial information through intermittent pulses, feeding that data into the overlord's central nervous system. Because the information is processed as fast as it arrives, an overlord can navigate any environment and relay tactical data to the Swarm in real time. (Overlord (StarCraft II official site))

The overlord possesses a large, bulbous brain protected by a heavily armored weave of bone and cartilage, an organ of millions of nerves and synaptic contacts. Its cerebral structure is complex, with neural pathways woven throughout the body but concentrated in the lower section and legs, and it is through this system that the overlord relays commands to the Swarm. That nervous system makes the overlord a powerful psionic transmitter whose ability to broadcast psychic energy is unmatched. To preserve this capacity, the Zerg altered only the neurologically impotent parts of the Gargantis, such as the carapace and pulmonary chambers. (Overlord (StarCraft II official site); Project Blackstone)

Judgment and behavior#

Overlords, unlike most other Zerg breeds, typically only relay orders. They are technically capable of directly controlling lesser Zerg, but only with extreme difficulty. They can communicate thoughts and concepts to higher command breeds, including complete sentences. Overlords are fairly docile, and among their additional duties are tending young larvae and monitoring the progress of drones through a kind of instinctive telepathy. (Just an Overlord; StarCraft: The Dark Templar Saga: Shadow Hunters; StarCraft Compendium; StarCraft II: Wings of Liberty)

After the Queen of Blades was defeated at Char, some overlords tried to form pockets of organized Zerg in the manner of broodmothers. Some, particularly those Gargantis proximae originally assimilated into the Swarm, regained their free will upon going feral and were able to gather small broods of their own. (Just an Overlord)

Flight and physiology#

Overlords retain the thick outer shell of the Gargantis, which changed little during assimilation and is strong enough to resist a lightning strike. As space-faring creatures, an overlord's carapace pressurizes and seals whenever it flies through vacuum, a function regulated by two species of unidentified symbiotic organisms that die within seconds of being removed from their host, which has frustrated Dominion efforts to obtain living samples. (Overlord (StarCraft II official site); StarCraft: Shadow of the Xel'Naga)

For lift and motive power, overlords use helium-filled gas sacs. The helium is generated through an efficient respiratory system distributed across the carapace, with the excess stored in thick sacs that contract and expand to let the creature regulate altitude and propulsion at will. They move quite slowly. Because they must support many different strains of Zerg at once, overlords can sometimes exhibit spontaneous adaptive mutations that improve their own efficiency. (Overlord (StarCraft II official site); StarCraft II War Chest)

Transport and later capabilities#

With the correct growth stimuli, an overlord can carry other Zerg within hollows in its hide, becoming a deep-space transport. The importance of this role is reflected in the sheer number of overlords found accompanying Zerg forces. By the Second Great War, overlords could disgorge creep to prepare the ground for conquest, producing it by liquefying their internal organs and storing it in glands near the head, then regrowing those organs at will and modifying them to draw substance from inhospitable environments. By the same era, overlords could also metamorphose into overseers. On average during the Second Great War an overlord measured roughly eighteen meters in length, twelve in height, and ten in width. (StarCraft; StarCraft Compendium; Overlord (StarCraft II official site); StarCraft II: Wings of Liberty; StarCraft Field Manual)

Variants and feral overlords#

The overlord strain produced several notable forms. The Mastermind Overlord and the named individual Yggdrasill are recorded among its variant strains, and individuals such as the overlords known as Green Eyes and Purple Eyes are remembered by name. While most primal Zerg, such as those of Dehaka's pack, have evolved beyond the need for overlords, small numbers of primal overlords persist among the various packs. Overlords of the Leviathan Brood reflect the genetic mutations of the creatures beneath them, owing to their constant connection within the Swarm's hive mind. (Just an Overlord; StarCraft II: Heart of the Swarm; StarCraft II War Chest)