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Great Old One, Cthulhu

Cthulhu CR 30

XP 9,830,400
CE Colossal aberration (chaotic, evil, Great Old One)
Init +12; Senses darkvision 60 ft., true seeing; Perception +50
Aura unspeakable presence (300 ft., DC 30)


EAC 47; KAC 49
Fort +30, Ref +30, Will +26
Defensive Abilities Great Old One immortality, fast healing 30, insanity (DC 30), non-euclidean; DR 20/lawful and magic; Immunities Great Old One immunities, vacuum; Resist acid 30, electricity 30, fire 30, sonic 30; SR 41


Speed 60 ft., fly 200 ft. (Su, average), swim 60 ft.
Melee claw +45 (21d10+47 S plus grab) or tentacle +45 (21d10+47 B plus grab)
Multiattack 2 claws +39 (15d10+47 S plus grab), 4 tentacles +39 (10d12+47 plus grab)
Space 40 ft.; Reach 40 ft.
Offensive Abilities cleaving claws, constrict (8d6+47 B), trample (21d10+47 B, DC 30)
Spell-Like Abilities (CL 30th)

1/daygravitational singularity, mass inflict pain (DC 30), mind thrust (6th-level, DC 30), planar barrier, plane shift (self only), terraform
3/daydominate person (DC 29), feeblemind (DC 29), greater command (DC 29)
At willconfusion (DC 28), dream, fear (4th-level, DC 28), nightmare (DC 29), teleport (self only)
Constanttrue seeing


Str +17, Dex +8, Con +14, Int +11, Wis +11, Cha +8
Skills Acrobatics +45, Intimidate +45, Mysticism +50, Piloting +45, Sense Motive +45
Languages Aklo; telepathy 300 ft.
Other Abilities compression, living starship, tainted land


Cleaving Claws (Ex)

A single attack from one of Cthulhu’s claws can target all creatures in a 10-foot-square area. Make one attack roll; any creature in the area whose AC is equal to or lower than the result takes damage from the claw.

Great Old One Immortality (Ex)

In addition to the immunities and traits it gains from the Great Old One subtype, if Cthulhu is killed, his body immediately fades away into a noxious cloud of otherworldly vapor that fills an area out to his reach.

This cloud blocks vision as fog cloud but can’t be dispersed by any amount of wind. Any creature in this area must succeed at a DC 30 Fortitude save or be nauseated for as long as it remains in the cloud and for an additional 1d10 rounds after it leaves the area. Cthulhu returns to life, restored to full hit points and health with all remaining unused spell-like abilities after 2d6 rounds, manifesting from the cloud but is staggered for 2d6 rounds (nothing can remove this staggered effect). If slain again while he is staggered from this effect, Cthulhu reverts to vapor form again and his essence fades away after 2d6 rounds, returning to his tomb in R’lyeh until he is released again.

Non-Euclidean (Ex)

Cthulhu does not exist wholly in the physical world, and space and time strain against his presence. His apparent and actual position are never quite the same, granting him a 50% miss chance against all attacks. True seeing can defeat this miss chance, but any creature that looks upon Cthulhu while under the effects of true seeing must succeed at a DC 30 Will save or be driven catatonic, as per the feeblemind spell, for 1d6+1 rounds.

Tainted Earth (Sp)

Cthulhu’s terraform spell-like ability requires no materials components even while affecting permanent changes to the terrain.

Unspeakable Presence (Su)

Failing a DC 30 Will save against Cthulhu’s unspeakable presence causes the victim to immediately die of fright.

This is a death and fear effect. A creature immune to fear that fails its save against Cthulhu’s unspeakable presence is staggered for 1d6 rounds instead of killed.


Environment any (R’lyeh)
Organization solitary (unique)

Known to some as the Dreamer in the Deep, Great Cthulhu is the mightiest of the Great Old Ones. Cthulhu is represented often in artwork— particularly in sculpture, painting, and poetry, for his influence is particularly strong among such sensitive and creative minds. In these eldritch works of art, he is depicted or described as having a vaguely humanoid frame, but with immense draconic wings and an octopus-shaped head. His actual form is somewhat fluid—the Great Old One can shift and reshape his exact countenance as he wills, allowing him to occupy a smaller space than one might expect for a creature that stands over 100 feet tall.

It is fortunate indeed that Cthulhu is currently imprisoned on a distant planet within the sunken city of R’lyeh. There, the Great Old One slumbers away the eons in a state neither quite dead nor living, held in stasis by ancient magic and the potency of the Elder Sign, yet at times the city rises from the sea and the doors to his tomb open, granting Cthulhu limited mobility before he must return to his tomb.

Cthulhu Starship Statistics

Great Cthulhu can survive and even thrive in the hard vacuum that exists in the darkest voids between stars. His terrestrial (CR 30) form is completely functional in space, but he is also capable of traversing whatever star system he currently inhabits and even cross interstellar distances swiftly. The deranged writings of long dead prophets claim the Great Old had this ability long before the advent of Drift technology. The Great Old One has no crews or technological components, the listed starship “systems” are approximations; the common models they imitate are listed below. Cthulhu literally tears across the void by some combination of magic, psychic energy, and his vast alien force of will. His focused concentration strains physicality.

Encountering Cthulhu in space is different than bracing against his malevolent presence planetside.

The Great Old One assumes a larger size, unfettered and unrestrained by normal space and the prosaic reality that mortals exude. Looking at Cthulhu’s size through the lens of game mechanics, Lovecraft describes Cthulhu as being over 100 feet tall. This exceeds the Colossal size of his terrestrial stat block, and he has the compression special ability to compensate and explain why this is possible.

Whereas the starship version of Cthulhu is Huge to provide an appropriate challenge. Yet this puts his size at least 800 feet long. The GM should consider that Cthulhu does not interact with three-dimensional space like mortal beings. He is almost always the size that he needs to be in context to when the PCs encounter him; on a planet, in outer space, or drifting in hyperspace.

Cthulhu’s alien nature notwithstanding, thanks to high-energy shields, particle weapons, and nuclear missiles (in an environment where collateral damage is a lesser priority) the power differential between mortal and demigod shifts.

His unspeakable presence is blocked by shields and longer distances, while computer-assisted targeting ignores the insanity his true visage conveys. A capital starship armed with the best defenses and weaponry stands a small chance of survival, although Cthulhu remains immortal even in the outer darkness.

Cthulhu (Starship Form) Tier 18

CE Huge starship aberration
Speed 10; Maneuverability average (turn 3); Drift 2
AC 36; TL 38
HP 280; DT 5; CT 56 Shields heavy 480 (forward 120, port 120, starboard 120, aft 120)
Attack (Forward) tentacles +18 (4d4 plus immobilize), vortex cannon +18 (2d12x10 plus vortex)
Attack (Port) heavy persistent particle beam +18 (10d6), claw +18 (4d6 plus ripper)
Attack (Starboard) heavy persistent particle beam +18 (10d6), claw +18 (4d6 plus ripper)
Attack (Turret) heavy gravity gun +18 (6d6 plus traffic beam)
Skills Computers +45, Engineering +45, Piloting +45 Power Core Gateway Ultra (500 PCU), Micron Ultra (80 PCU); Drift Engine Signal Booster; Systems advanced long-range sensors, mk 8 armor, mk 10 defenses, power core housing, upgraded light weapon mounts; Expansion Bays none
Other Abilities Great Old One immortality, living starship, no breath

Claws (Ex)

Cthulhu’s titanic claws on the port and starboard arcs are capable of slashing right into the hull of enemy ships but are largely deflected by functioning shields. The target vessel must be adjacent to either the port or starboard arc and be in an adjacent hex. Halve all damage dealt by the claws to shields.

Great Old One Immortality (Ex)

If Cthulhu’s HP is reduced to zero or less, he changes into a massive cloud of yellow gas which does not dissipate in the vacuum of space. Cthulhu reforms after 1d10 rounds, his shields restored, but he is unable to act (including making skill checks) for 2d6 rounds.

If slain again, he is exiled back to his tomb on R’lyeh. This ability is identical to the ability of the same name in his terrestrial stat block.

Living Starship (Ex)

Cthulhu has no crew, but can still take engineer, gunner, and pilot actions (one of each, in the appropriate phases) using the skill bonuses listed above. Modifiers for his size, speed, and maneuverability have already been factored into his statistics. Assume it has a base attack bonus of +18. Use the following table to determine the effects when Cthulhu takes critical damage. Cthulhu’s brain doesn’t take critical damage conditions.

Tentacles (Ex)

Cthulhu’s gigantic tentacles dangle from his forward arc and are powerful enough to grab a starship and hold it in place, making it easier for the Great Old One to blast the vessel with its vortex cannon attack. Cthulhu can make a tentacle attack only against a Huge or smaller starship that is in his forward firing arc and in an adjacent hex adjacent. If the attack deals Hull Point damage to the target, that vessel can’t move unless its pilot succeeds at a DC 30 Piloting check as an action during the helm phase. A starship that is immobilized in this way takes a -2 penalty to AC and it’s target lock.

Critical Damage Effects
d% System Effect
1-30 Weapons Array Randomly determine one arc containing weapons; condition applies to all gunner actions using weapons in that arc.
31-60 Propulsion Condition applies to all pilot actions
61-90 Heart Condition applies to all engineer actions, except when patching or repairing the heart.
91-100 Brain During the next round, each of Cthulhu’s attempted actions have a 25% chance of failure.
Section 15: Copyright Notice

Alien Bestiary (Starfinder) © 2018, Legendary Games; Lead Designer: Jason Nelson. Authors: Anthony Adam, Kate Baker, John Bennet, Eytan Bernstein, Robert Brookes, Russ Brown, Duan Byrd, Jeff Dahl, Robyn Fields, Joel Flank, Matt Goodall, Robert J. Grady, Jim Groves, Steven T. Helt, Thurston Hillman, Tim Hitchcock, Nick Hite, Daniel Hunt, Mike Kimmel Marshall, Isabelle Lee, Jeff Lee, Lyz Liddell, Jason Nelson, Richard Pett, Tom Phillips, Alistair J. Rigg, Alex Riggs, Wendall Roy, Mike Shel, Neil Spicer, Todd Stewart, Russ Taylor, Rachel Ventura, Mike Welham, George Loki Williams, Scott Young.