Great Cthulhu

Great Cthulhu

CR 21; XP 409,600
CE Great Old One of cataclysms, dreams, and the stars
Primary Source H. P. Lovecraft, “The Call of Cthulhu”


Domains Chaos, Evil, Madness, Void
Subdomains Deep Space, Insanity, Nightmare, Stars
Favored Weapon dagger
Symbol complex rune surrounding an open eye
Temple caverns, coastal churches, hidden coves, remote islands
Worshipers deep one hybrids, doomsayers, dreamers, insane artists
Servitors deep ones, starspawn

Influence Stage 1 (DC 27)

Speed 40 ft., fly 80 ft., swim 40 ft.
Area 80-ft. radius; Nucleus 30-ft. square
Effects devouring, non-euclidean geometry, telepathic assault (fear)
Proxy starspawn (see page 385)
Escalation In order to advance to stage 2, Cthulhu must successfully use his devour effect 10 times.

Influence Stage 2 (DC 30)

CR 24; XP 1,228,800
Speed 500 ft., fly 1,000 ft., swim 500 ft.
Area 400-ft. radius; Nucleus 100-ft. square
AC 42; Saves +25; hp 520
Effects devouring, non-euclidean geometry, telepathic assault (despair)
Escalation In order to advance to stage 3, Cthulhu must successfully use his devour effect 1,000 times.

Influence Stage 3 (DC 32)

CR 27; XP 3,276,800
Speed 2,000 ft., fly 4,000 ft., swim 2,000 ft.
Area 1 mile; Nucleus 300-ft. square
AC 45; Saves +28; hp 640
Effects devouring, non-euclidean geometry, telepathic assault (anarchy)
Escalation In order to advance to stage 4, Cthulhu must successfully use his devour effect 100,000 times.

Influence Stage 4 (DC 35)

CR 30; XP 9,830,400
Speed 2 miles, fly 4 miles, swim 2 miles
Area 10 miles; Nucleus 1,000-ft. square
AC 48; Saves +31; hp 760
Effects devouring, devastation, non-euclidean geometry, telepathic assault (global enslavement)


Combat Cthulhu can be defeated through damage. At influence stage 1, if the starspawn that serves as Cthulhu’s proxy is slain, Cthulhu is banished and his essence returns to R’lyeh to slumber once more. His slumber has no minimum duration: the conditions that woke him from slumber can happen again at any point, when the stars are right. At higher influence stages, Cthulhu’s size and power outstrip those of a creature that can be confronted in the classic sense, but damage can still affect him, forcing him to de-escalate to a lower stage from which he must devour anew to increase stage once again. A miracle or wish can automatically force Cthulhu’s influence stage to shift down by 1, to a minimum of influence stage 1.

At influence stages above 1, damage to Cthulhu is tracked as normal for combating influences. When an influence stage’s hit points are reduced to 0, Cthulhu’s influence decreases by one stage but has maximum hit points for that stage.

Influence Effects

Devouring Great Cthulhu gains power and increases his influence stage by devouring intelligent, living creatures, body and soul. For the purposes of tracking the progress of his increasing power, it is convenient to use a humanoid as a unit of measurement. Physical size is largely irrelevant when it comes to devouring. At the GM’s option, creatures of lesser soul and/or intelligence (i.e. animals, vermin, beasts) could count as fractions of a humanoid, while creatures of greater soul and/or intelligence (such as powerful outsiders, dragons, or heroic adventurers) could count as more.

When a creature begins its turn within the area of Cthulhu’s influence, it must make a successful Reflex save to avoid being snatched up by Cthulhu’s flabby claws and tentacles. Failure indicates the victim must make a successful Fortitude save to avoid being instantly consumed. On a successful Fortitude save, the victim is considered grappled. Creatures held in Cthulhu’s grip do not take damage, for Cthulhu must devour living bodies in order to grow. Physical escape from Cthulhu’s clutches is practically impossible, and requires a successful Escape Artist or combat maneuver check against CMD 55 + influence DC.

Magical methods, such as teleportation or freedom of movement, are likely to offer the only real route to escape for such a victim. A victim must continue to make successful Fortitude saves at the start of each turn in order to avoid being consumed. A victim that is consumed by Great Cthulhu is immediately slain and all carried gear is lost or destroyed (save for artifacts, which are left behind or shunted into other dimensions or realities at the GM’s whim). Only miracle, true resurrection, or wish can restore someone slain in this manner to life. Creatures in Cthulhu’s clutches when he is defeated are released, but there’s a 75% chance that upon release they are dropped from a great height and take 20d6 falling damage.

In a densely populated area, you can assume that Great Cthulhu can successfully devour a number of panicking humanoids equal to 1d20 times his current influence stage in a single round. At influence stage 2 or higher, each humanoid Cthulhu devours heals the influence by 20 HP at stage 2, 50 HP at stage 3, and 100 HP at stage 4.

Devastation The area within Cthulhu’s influence is wracked with powerful storms, earthquakes, and tsunamis as appropriate. Cthulhu himself is not impacted by these events, since by this time he has reached his maximum level of influence and those who perish from the disasters cannot be devoured.

Non-Euclidean Geometry Reality and the fundamental laws of physics go mad in the presence of Great Cthulhu. Creatures within the area of his influence suffer an increasing number of disorienting and strange effects, as detailed below. These effects are cumulative—at influence stage 4, all four stages of effects are active.

Within his home city of R’lyeh, the effects of Cthulhu’s non-Euclidean geometry always function as if he were at stage 4 and always have a minimum area equal to the size of R’lyeh itself.

Influence Stage 1: Allies and minions of Great Cthulhu have their reach doubled. Enemies of Great Cthulhu have their reach halved. If a creature has a reach of 5 feet, its reach is instead reduced to 0.

Influence Stage 2: Physical routes change, becoming dead ends or circles. The terrain and architecture you traveled the previous round will be different if you return to it. The presence of cover, difficult terrain, or the like shift from round to round (randomly or at the GM’s discretion), but generally do so in ways advantageous to Cthulhu or his minions.

Influence Stage 3: If a foe of Cthulhu moves more than 5 feet during its turn, that creature has a 25% chance of entering an area of geometry where it physically cannot exist. When a victim is exposed to such a reality, it can avoid the effect with a successful Reflex saving throw. If it fails, it vanishes, and is transported to somewhere else in the universe (randomly or at the GM’s discretion). If the saving throw was a natural 1, the victim instead winks out of existence, along with all of its gear (artifacts are not destroyed by this effect, but are transported elsewhere). Creatures lost in this way can only be restored to life via miracle, true resurrection, or wish.

Influence Stage 4: The chance of one of Cthulhu’s foes stumbling into dangerous geometry increases to 50% per round. Additionally, each round, there’s a 25% chance that a dangerous creature from another dimension may emerge from strange angles or warped reality. Shoggoths and starspawn and other aliens of similar power are typical arrivals.

Telepathic Assault All creatures within the area of Cthulhu’s influence must make a successful Will saving throw at the start of their turns or become overwhelmed with consuming terror and madness. The exact effects of this madness depend on what stage of influence Cthulhu has achieved. Once a creature fails this saving throw, the effects persist until the creature moves out of Cthulhu’s influence. A creature suffering from Cthulhu’s telepathic assault when his influence escalates is automatically affected by the new effect and is no longer affected by the previous effect. This is an mind-affecting, insanity effect.

Fear: At stage one, those who succumb to Cthulhu’s telepathic assault become shaken. This effect stacks with multiple failed saves, first to frightened, and finally to its maximum effect of panicked.

Despair: At stage two, those who succumb to Cthulhu’s telepathic assault cower in fear.

Anarchy: At stage three, those who succumb to Cthulhu’s telepathic assault suffer from overwhelming paranoia and hallucinations, and find it impossible to tell friend from foe. Under this effect, a creature babbles incoherently unless another creature is within 30 feet, in which case the victim uses every resource it has available to attack the perceived foe with intent to kill.

Global Enslavement: At stage four, those who succumb to Cthulhu’s telepathic assault fall under his control and do his bidding as meat puppets. This effect functions as dominate monster.

Cthulhu himself, with the rest of his species, is currently buried in the vast corpse-city of R’lyeh beneath the sea. Cthulhu exists in a sort of living death but can be awakened, and his influence can be summoned elsewhere. His mind is not asleep and remains keenly active.

Cthulhu Rising

Cthulhu’s final rising will be accompanied by thousands or perhaps millions of starspawn, his kith and kin. He is like unto them, though vastly more powerful. Just as the rest of his race can, Cthulhu can plunge from world to world through space, and so could travel or be brought to any planet.

The Devouring

When just awakened, Cthulhu manifests only part of his powers. When Cthulhu first rises, his tentacles and flabby claws can snatch people up and physically eat them. As he grows, Cthulhu’s tentacles and shapes begin to shift greatly. By influence level 2, he can flick out pseudopods or claws for hundreds of yards to grasp his prey and return them to his maw, devouring them in an instant. Simply fleeing is no longer enough to avoid his presence. By influence level 3, Cthulhu seeks to devour an entire city or small region in order to unleash his full power. Since mountains of protoplasm are by now rising from the sea, he likely faces little challenge in doing so.

At the zenith of his power, Cthulhu’s height grows to miles. His head rises above the clouds and his visage can be seen for hundreds or even thousands of miles. His slithering, more-than-mountainous magnitude causes earthquakes, sends forth tidal waves, and even attracts storms. Clouds form against his midriff and shoulders and his progress brushes them away.


When Cthulhu is awakened, his mental powers stretch for miles, potentially blanketing a planet. Everyone nearby has visions of Cthulhu’s mind and perceives his unthinkable goals. While he is largely incomprehensible to mortals, the effects of this telepathy are profound. Most nearby humanoids and animals are filled with consuming terror, hallucinations, and shrieking madness. This telepathy is one reason that terrestrial armies are unable to block or destroy him: most soldiers will just lay screaming on the ground in a fetal position, unable to even draw a weapon.

Cthulhu in Combat

Mortals brave and foolish enough to challenge the Great Old One in combat face a truly nightmarish encounter that is less like a battle and more a desperate attempt to survive a world gone mad. Reality twists, bends and ceases to make sense, while Cthulhu’s unrelenting psychic assault maddens even the strongest minds. His servitors come boiling out of the edges between realities, and the Great Old One himself sweeps mortals into his maw with little enough effort.

A battle with Cthulhu should be the climactic end of a campaign, as few could ever expect to survive.

Sandy's Notes: Non-Euclidean Geometry

Cthulhu and especially R’lyeh cover all nearby terrain in a pall of disorienting geometries. Distances change as if in a nightmare. If you seek to flee Cthulhu, you’ll find that the path stretches out longer and longer. If his minions pursue you, you’ll find that they somehow are able to catch up, like a villain in a slasher movie, as though time and space provide no barriers to their movement. It is not teleportation, however, but the distortion of distances.

The most lethal effect of this geometry is that sharp angles sometimes act strangely as Cthulhu nears full power. They can swallow up individuals, transporting them to other worlds or dimensions. For example, if you are being chased through a forest, you might see someone run behind a tree as he flees, and then never come out the other side. He has somehow “fallen through” the dimensions and is no longer in the material world.

This website uses cookies. See the Legal & OGL page for important information. Any material NOT covered by the Open Game License Version 1.0a is covered by the Creative Commons Attribution-ShareAlike 3.0 License.