Real Name: Mercurio (nearest English equivalent; name in own language unrevealed)

Identity/Class: Extraterrestrial (Gramosian) mutate and technology user

Occupation: Warrior;
government psycho-explorer

Group Membership: Led an army of Gramosians; formerly "The Stranger's prisoners"

Affiliations: Agent of the High Lord of Gramos;
former pawn of the Overmind and Zarrko the Tomorrow Man;
briefly allied with Karnilla, Sif, Thor and the rest of the Asgardians

Enemies: Captain America (Steve Rogers), Captain Mar-Vell, Hildegarde, Kree/Ruul, Makkari, Odin, Quasar, Ronan the Accuser, Squadron Supreme (Dr. Spectrum, Moonglow (Arcanna), Power Princess, Shape, Skylark, Whizzer), Stranger, Thor Odinson, Thor (Masterson), Warriors Three (Fandral, Hogun, Volstagg), Xorr the God-Jewel

Known Relatives: None

Aliases: Fourth-Dimensional Man, the 4-D Man, Karl Sarron

Place of Birth: Planet Gramos, third from the sun in the Sekar system, Milky Way Galaxy

Base of Operations: Currently unknown (last seen on Earth)
formerly the planet Gramos

First Appearance: (As Karl Sarron) Thor I#204 (October, 1972); (as Mercurio) Thor I#208 (February, 1973)

Powers/Abilities: Mercurio can lift 10 tons, and he is far more dense and durable than the average human being, able to resist great extremes in temperature, certain lethal radiations, and explosive forces up to the range of small anti-tank weaponry. He can fly by harnessing anti-gravitons (particles that repel gravitions, the smallest particles that contain a gravitational force) at a maximum speed of 40 miles per hour.

Like many Gramosians, Mercurio can generate heat by using psionic energy to accelerate the motion of molecules. However, due to his transformation, he can only do so from his left side. From his right side, he can generate cold by a similar psionically-controlled deceleration of molecules. He can generate maximum temperatures of 2,900 degrees Fahrenheit (melting point of iron) to -440 degrees Fahrenheit.

Neither Mercurio nor his race can survive in the vacuum of his space unaided. They employ transparent life-support suits providing them with their atmospheric requirements for 6 hours before having to be replaced.

After taking human form for a length of time, Mercurio's mind was apparently re-programmed for human languages, and he could no longer speak his native tongue. He regained the ability, however, after returning to his Gramosian form.

He sometimes travels via spaceship, or by teleportation via his Dimensional Oscillator.


Height: 6' (by approximation)
295 lbs. (by approximation)

Other Distinguishing Features: His right half is colored red, while his left half is dark-blue.
("normal" Gramosians are all dark-blue)




History: (Thor I#216 (fb)/Official Handbook of the Marvel Universe#7) - On the opposite side of Earth from the Milky Way galaxy, the world of Gramos had reached the height of technology and culture. However, a freak space-warp opened near Gramos, causing the polarity of their world to be inexplicably altered such that its atmosphere transformed, admitting only the extremes of the electromagnetic wavelength. Deprived of ordinary life-sustaining light, many Gramosians began to go mad and then die.

In an effort to seal the space-warp, the High Lord of Gramos dispatched the world's top psycho-explorer--Mercurio--to Earth. Gramosian scientists beamed Mercurio's mind into the body of wealthy landlord Karl Sarron.



(Thor I#204 (fb) - BTS) - Mercurio, as Karl Sarron, bought the building at which Dr. Donald Blake practiced. In Donald Blake's absence Sarron had Blake's office closed.

(Thor I#216 (fb)) - Over a period of months, Mercurio accumulated energy residue left behind by Blake's transformations into Thor from inside Blake's office. He hoped to gain enough power to return him to his natural form, from which he could then transfer Earth's electromagnetic field to Gramos, restoring its polarity.

(Thor I#204 (fb)) - When Blake returned to Earth from a lengthy adventure in outer space as Thor, he was surprised that his office was closed. Sarron introduced himself to Blake as the building's new owner, and told Blake that he would have to prove his former arrangements and payments to Sarron before Blake's office would be opened again. Sarron expected to see Blake in his office next Monday.

(Thor I#208) - After receiving a potent charge from Blake's office into his Dimensional Oscillator, Mercurio contacted the leader of Gramos, who reiterated the urgency of his mission. Mercurio used the oscillator to restore his true form, but found it only possessed the charge to do so halfway, leaving only his left half his normal dark-blue, with his right half now red. Realizing he needed more power directly from Thor to complete the transformation, he waited for Thor to return and then attacked him. Mercurio continued to accumulate power as they fought, and Thor found all of his power ineffective against him. When the Warriors Three arrived to help Thor, he fled, returning after reviewing some literature as Don Blake. A plan in mind, Thor hurled a steel girder at Mercurio, who melted it, but was then coated in molten metal. The iron covering contained the forces within Mercurio so thoroughly that his powers overloaded, and Mercurio was seemingly consumed in the process.

(Thor I#214 (fb)) - Mercurio seemed to die, but was instead summoned to another level of space, where he encountered Xorr the God-Jewel. As he was accidentally brought there by Xorr, he was then transported back to Gramos, before the presence of his leader.

(Thor I#216 (fb)) - Mercurio's leader reaffirmed the importance of his mission, sending him into the Dark Nebula to claim the power of the God-Jewel to save their world.

(Thor I#214) - Mercurio led a force of Gramosians to assault the Miners of the Dark Nebula (Kagg, Quellor, Rothgar) in order to gain the form of Xorr. However, the Miners were assisted by a force of Asgardians who had been traveling through that region of space, including Hildegarde, Odin, Thor, and the Warriors Three. The Asgardians fought the Gramosians, gaining the upper-hand, but the Miners then reawakened Xorr itself, which threatened to destroy them all.

(Thor I#215) - Xorr incapacitated both the Gramosians and the Asgardians, who awakened in a subterranean chamber. They fought the Miners again, but they discovered that Xorr had been mobilized by another ship and was leaving. They pursued in the Asgardian Starjammer longship, but when they reached it, Xorr threatened to destroy its prisoners--Sif and Karnilla--if they resisted it further. The threat held little sway over Mercurio and his men, but Thor agreed to submit to save his lover. Mercurio cursed him as a coward.

(Thor I#216) - Thor forcibly stopped Mercurio and the Gramosians from attacking Xorr. Mercurio took his warriors and vanished, but they soon returned in spaceships and attacked anew. However, Mercurio convinced Thor that they must join forces against Xorr, and Mercurio used a rapid combination of cold and heat to shatter the section over Sif and Karnilla, freeing the goddesses. Thor then brought Mercurio, Sif, and Karnilla back to the Starjammer, where they fled in time to escape Xorr's overloading himself on the energies of a supernova explosion. Xorr exploded into countless fragments, which the Gramosians gathered up to take back to Gramos.



(Captain Marvel I#51 (fb) - BTS) - The energies of the Xorr fragments restored Gramos' polarity, saving the Gramosians. The changes returned them to peace and contentment, but Mercurio found himself unable to live with this "slug-like life...basking in the God-Jewel's rays." Over a period of months, Mercurio began organizing an invasion force to attack Earth, and he decided that the Kree Omni-Wave Projector would be the ideal weapon for their conquest.

(Captain Marvel I#51) - Mercurio returned to Earth and attempted to use a Beta-Wave Thought Processor to steal the secrets of the Omni-Wave Projector from Captain Mar-Vell, but Mar-Vell detected the scan and destroyed the processor. Mar-Vell then attacked Mercurio, who explained that he only wished to use the Omni-Wave to save his world, claiming that Xorr's energies had faded and only the Omni-Wave could re-energize them. Mar-Vell agreed to accompany Mercurio, but as soon as they arrived, the Gramosians ambushed Mar-Vell. Having suspected treachery, Mar-Vell was prepared and dodged the initial attack and fought off the Gramosians. Mercurio then attacked, but Mar-Vell (who had experienced the cold of space and heat of the stars) resisted his power and flattened him with a single punch. Mar-Vell then accessed Mercurio's Dimensional Oscillator to return to Earth.

(Thor I#440) - Mercurio was one of several beings summoned from across time to battle Beta Ray Bill, Thor (Masterson), and Thor (Dargo Ktor). Though Masterson was inexperienced against Mercurio's power, the Gramosian was dazed and sluggish from his trip through time, and he quickly fell in battle.

(Quasar#14 (fb) - BTS) - At some point, Mercurio became a prisoner of the Stranger and was held within his laboratory world.

(Quasar#14,[15],16) - Mercurio was summoned by the Overmind, mentally enslaved, and sent to battle the Stranger and several heroes opposing the Overmind. Mercurio dropped Lady Lark/Skylark with a heat blast, but was then quickly flattened by a series of punches from the Whizzer of Earth-S.

(Maximum Security#2/Captain America III#36) - During the events of Maximum Security, Mercurio returned to the form of Karl Sarron. Encountering and assisting Captain America against some of the aliens trapped on Earth, Sarron then told Captain America that he could use his Dimensional Oscillator to banish all of the aliens from Earth, though he required the energy of Cap's shield to do it. Cap, suspecting a trap, went along with Sarron until he revealed himself as Mercurio and tried to destroy Cap. Fighting back, Cap tore his shield from the oscillator and smashed Mercurio with it. The energies with which the shield had been charged caused a feedback that apparently caused Mercurio to explode.

(Maximum Security#3) - Mercurio was apparently one of the aliens who joined the Avengers and other heroes of Earth in fighting the forces of Ronan and the Ruul/Kree to end the aliens' banishment to Earth.

Comments: Created by Gerry Conway, John Buscema, and Vince Colletta.

Profiles in the Official Handbook of the Marvel Universe I#7 and the Master Edition.

The initial story in Thor I#208 said that Mercurio had been absorbing Thor's powers for six years, but the OHotMU clarified it to months.

It is unclear to me whether Mercurio was sent to Earth as part of Maximum Security (in which case he would have to have been imprisoned in one of the interstellar prisons whose inmates were sent to Earth--another unseen story--or whether he returned to Earth with some of the others who had escaped the Stranger's laboratory world).

Captain America III#36 perpetuates the myth that Captain America's shield is made of a synthesis of adamantium and vibranium. That's not correct, and Kurt Busiek detailed the reasons for this in Avengers Annual 1999. Captain America's shield was created in 1941 by Myron MacLain, and he synthesized a steel alloy that bonded to vibranium in a process that he has never been able to duplicate. This material HAS been referred to as proto-adamantium, but it was not an adamantium/vibranium hybrid. Adamantium was not invented by Myron MacLain until decades later, when it was first used to create Ultron (although Lord Darkwind apparently developed it in parallel of MacLain). The exact differences are unknown.

Never really got what was supposed to be Four-Dimensional about him. It's just a confusing term, because he does not come from another dimension, but rather a distant planet in the Milky Way galaxy in Reality-616.

For some reason, despite having profiles all over the place, including different editions of the OHotMU, this has been one of the most requested profiles from the Appendix site. Finally, I bow to the dozens of requests.

Thanks to Luis Dantas for pointing out Mercurio's first appearance as Sarron in Thor I#204.

  Mercurio has no known connection to:

The "Fourth Dimension" has no known connection to:

Dimensional Oscillator

A Gramosian device with which Mercurio could open a portal to Gramos. He often required a power source to utilize it, such as energy left behind by Thor's transformations or from Captain America's shield.


--Thor I#208 (Captain Marvel#51, Captain America III#36



Official Handbook of the Marvel Universe, Master Edition#7
Thor I#214, p15, pan3 (face)
Thor I#214, p14 (powers)
Thor I#208, p11, p5 (oscillator)
Thor I#208, p7, pan2 (Sarron)

Thor I#204 (October, 1972) - Gerry Conway (writer), John Buscema (pencils), Jim Mooney (inks), Roy Thomas (editor)
Thor I#208 (February, 1973) - Gerry Conway (writer), John Buscema (pencils), Vince Colletta (inks), Roy Thomas (editor)
Thor I#214 (August, 1973) - Gerry Conway (writer), Sal Buscema (pencils), Jim Mooney (inks), Roy Thomas (editor)
Thor I#215-216 (September-October, 1973) - Gerry Conway (writer), John Buscema (pencils), Jim Mooney (inks), Roy Thomas (editor)
Captain Marvel I#51 (July, 1977) - Scott Edelman (writer), Al Milgrom (pencils), Terry Austin & Al Milgrom (inks), Archie Goodwin (editor)
Thor I#440 (December, 1991) - Ron Frenz & Tom DeFalco (writers), Ron Frenz (pencils), Al Milgrom (inks), Ralph Macchio (editor)
Quasar#14-16 (September-November, 1990) - Mark Gruenwald (writer), Mike Manley (pencils), Dan Panosian & Keith Williams (#16) (inks), Len Kaminski (editor)
Maximum Security#2 (December, 2000) - Kurt Busiek (writer), Jerry Ordway (pencils), Will Blyberg, Paul Ryan, Walden Wong (inks), Tom Brevoort (editor)
Captain America III#36 (December, 2000) - Dan Jurgens (writer/pencils), Art Thibert (inks), Bobbie Chase (editor)
Maximum Security#3 (January, 2001) - Kurt Busiek (writer), Jerry Ordway (pencils), Will Blyberg, Paul Ryan, Mark McKenna (inks), Tom Brevoort (editor)
Captain America III#36 (December, 2000) - Dan Jurgens (writer/pencils), Art Thibert (inks), Bobbie Chase (editor)

First Posted: 04/19/2004
Last updated: 12/29/2019

Any Additions/Corrections? please let me know.

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