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Mental (also known as Tah-Um, Chaad Sheen, The One Infinite or Notorious Mental) is the main antagonist of the Serious Sam series. His appearance has been kept a secret since the series' inception. 


Mental is the last of the Hum-Tah (the Infinite Ones), a species of god-like beings that once ruled over intergalactic empire's for eons.

It is suggested that Mental wipes the galaxy clean of intelligent life once every one hundred thousand years. In between these cycles of war, he enters a state of hibernation and supposedly leaves autonomous machines (mostly around homeworlds of extinct species) on guard, watching out for any activity in the galaxy.


Mental's appearance is unknown. One can speculate that his appearance is somewhat hinted by logos seen on some of his army's vehicles or creatures, where he's depicted as a Cthulhu-like creature (as seen in Serious Sam 2).

Mental's hand appears in a cutscene in Serious Sam: Next Encounter, but this game has been qualified as non-canon by Croteam[1], hinting that it must not be taken into consideration.

In Serious Sam: Tormental, Mental appears as a large black bat-like creature with horns, a menacing-looking eye and a big gaping mouth. This may not be his true form, however, as the game takes place inside of his mind. His image is also featured on the game's logo.


Mental's true name is unknown, there he is known by several aliases.

  • "Mental" was a name bestowed by humanity (and several NPCs in Serious Sam 2) because of how chaotic and insane his army is. He is also called "Notorious Mental" by NETRICSA. However, his home is indeed called "Mental Residence" by his daughter Judy Mental in Serious Sam 3: BFE and "Mental Institution" in Serious Sam 2.
  • "Chaad Sheen" ("wizard exterminator" in Sirian) was a name bestowed by the Sirians before they were wiped out by his armies.
  • "Tah-Um" ("The One Infinite" in Eillian) was a name bestowed by the Eillians and is believed to be Mental's original name, as confirmed by a Gnaar when it says that Tah-Um is going to "moon" Sam in Serious Sam 3.
  • "Khad Shain" is the name that the Witch-Brides of Achriman knew him as before they were corrupted into serving him.

Powers and abilities[]

Not much is known about Mental's abilites, though as his species are god-like entities, it's possible that he is extremely powerful. Despite this, he usually relies on his forces for whatever he commands them to do. He has great knowledge of technology and magic - as seen in his forces - and the many technological devices he's assembled such as the Life Control Unit, a device used to control resurrected infantry. He can also grant magical powers to other species, such as the Aludran Reptiloids, or use magic to reanimate the skeletons of extinct creatures, in this case the Kleer Skeleton.

A concept of Mental in the #howtokillsam series shows him using a laser beam on Sam from his eye, setting him on fire.[2] Whether or not he can actually do this is not known.



Mental is the last of the Hum-Tah, or the Infinite Ones, extremely powerful entities of unknown nature, who once ruled over intergalactic empires for eons. First mentions of their existence come from the ancient race of Eillians, who discovered ruins of long forgotten civilizations:

"Of the infinite, there are three kinds:
Lost ones, they are lost in infinity
And useless.
Ones that create, they were our gods
They were finited.
Ones that destroy, they were banished.
But The One Infinite is still.

This ancient message hints that the Hum-Tah, with the exception of one, are all extinct or banished from the universe. Tah-Um, being the only surviving Hum-Tah in the galaxy, was slowly driven mad by loneliness,to the point of insanity,and thus,developed a deep hatred towards the younger races, as they were able to avoid the terrible fate which befell upon him.

It's unknown when Tah-Um started his genocidal campaign to wipe out all sentient life in the galaxy, but many believe that he has been doing this for thousands, if not millions of years. Allegedly, soon after this discovery, the Eillians were spotted and exterminated by Tah-Um. At least a hundred thousand years after, the Sirians too, were wiped out by Mental's armies once they discovered traces of those who came before him.

Battling the Sirians[]

Many, many years after the fall of the Ellians, the Sirians appeared and helped more primitive species, such as the Kleers. During their travels, the Sirians stumbled upon ruins of the ancient Eillian civilization. Soon after, they translated their old song about the Hum-Tah, revealing the danger that Mental poses. At the same time, coincidentally or not, Chaad Sheen ("Chaad Sheen" was a name bestowed by the Sirians) found the Sirians, too.

Mental began waging a war against them, executing their people and resurrecting and recruiting the fallen soldiers as members of his army. Soon enough, he had wiped out all of Sirius and its colonies, including firebombing the Kleers and reanimating their skeletons. Unknown to Mental was that Sirians had one more of its search parties out in the universe, which resided on Earth. These Sirians had left much of their technology and warnings about Mental to the humans.

After wiping out the Sirians, Mental hid in an unknown region of space, leaving an array of autonomous machines around Sirius, disguised as an asteroid field, for the purpose of alerting him should any intelligent life appear.

War on humanity[]

Main article: Mental War

Around two thousand years later, humans discover old Sirian technology buried under old Ancient Egyptian ruins. After some reverse-engineering, mankind obtained ways to travel between stars with ease. An exploratory force lead by Earth Defense Force Captain Sam Stone was sent to chart out the remains of Sirius for a corporation. However, there was something unusual; the planet was surrounded by an asteroid bubble not mentioned in the records. Sam examined one of the asteroids, accidently setting off an alarm system in the process and bringing Mental back one hundred years earlier than usual.

Having laying dormant for so long, Mental immediately shows extreme aggression towards the humans. He sends in his armies at full force, until the humans eventually suffered the same fate as the Sirians.

Mental's army[]

Main article: Mental's Horde

The logo representing Mental's army.

Mental utilizes both technology and magic to achieve his goals. The diversity can be seen in his army, where he uses cyborgs, executed enemy soldiers raised from the dead, spaceships, biological weapons, reanimated skeletons of long extinct races, manufactured clones of human soldiers, low-grade models made from sewn-together parts of other units, telekinetic sorcerers, clones trained in casting spells, creatures made out of pure magic, robots, trained war mammals, mercenaries, and even plain vehicles. These creatures are often sent in very large numbers, which is possibly why Mental always manages to defeat any species he encounters.

He also recruits primitive races to bolster his ranks. He has established agreements with a race called the Aludran Reptiloids in order for them to work for him, and has even tampered with the evolutionary paths of some creatures so he can mold them into troops for his own purposes. He uses several methods to coerce races into working with him. In the case of the Aludran Reptiloids, he offered them magical combat abilities. In other cases, such as the Zorgs, he simply paid for massive amounts of disposable troops.

This isn't to say that Mental has no intelligent creatures working with him; General Maxilla, Ugh-Zan III, and Ugh-Zan IV appear to be intelligent enough to serve as admirals or generals in Mental's army. Also, Mordekai the Summoner was intelligent enough to properly use and research magic. These are most likely exceptions.


Main article: Mental-Altani

In Serious Sam's Bogus Detour, Mental forges an alliance with a planetary mining company known as the Altani corporation. He uses them to start producing a mutagenic substance called the 'ooze' on a massive scale, and then has the company go from planet to planet and conduct various experiments on the native lifeforms. One of the planets that the company found was Earth; a planet Mental was already familiar with. Once Mental-Altani found Earth, Mental had them use the ooze on the Earth's ecosystems, wreaking havoc on the environment and polluting its oceans. His main objective here was to wipe out the human race and prevent Sam from saving the fate of humanity in the past.

As Mental was fascinated with the properties of the ooze, he had Mental-Altani start experimenting on his own troops as well, in an attempt to enhance their abilities and make them tougher than usual. One of the test subjects used were Gnaars, but after they were exposed to the ooze, they became hostile, so the corporation decided to contain them inside vats so they couldn't escape.


Serious Sam: The First Encounter[]

After Sam enters the Time-Lock, he warps back to Ancient Egypt. As expected, the Time-Lock alerts Mental from that time period that there is intelligent life on Earth, so he sends some of his forces to slaughter humans back then. This Mental is unaware of Sam's abilities at first, and sends only weak forces at him. However, after Sam slaughters them, he begins sending in more and stronger forces, such as the Highlander Aludran Reptiloid, against him. Sam still manages to slaughter every creature that Mental sends at him.

Knowing that something major is up, he sends Ugh-Zan III at Sam while he is approaching the Great Pyramid. Sam manages to retreat to the Great Pyramid and reach its top where the SSS Centerprice is parked. Ugh-Zan III scales the pyramid in order to finish off Sam, but Sam manages to manipulate the ship's security system to defeat Ugh-Zan III. After Ugh-Zan III is slain, Sam boards the ship and calls up Mental, who is not at home at the moment.

Serious Sam: The Second Encounter[]

By the time Sam crash lands on Earth again, Mental is well aware of Sam's abilities and tries to stop him with stronger and newer forces from the start. He seems to be somewhat aware of Sam's plan to get a backup ship, as he does things such as installing an Exotech Larva in front of the portal to medieval Europe. He even manages to steal the Holy Grail, which is used to activate the backup Sirian ship Sam is looking for. However, he is unable to use or destroy it because he nor his creatures are authorized to use it, as they are seen as 'evil' and therefore are not within God's mercy. Sam manages to defeat the Holy Grail's guardian, Mordekai the Summoner, and uses it to activate the backup spaceship. Before he leaves, he 'confesses' to Mental and mocks him by pretending to apologize for killing his monsters and troops, then he tells Mental he is going to get him.

Serious Sam: Next Encounter[]

Mental makes a brief appearance at the start of the game where he tells the evil Serious Sam Clone that he shouldn't get into trouble nor mess with Mental's Time-Lock. During the scene, his hand can be seen; However, Croteam stated on Reddit that this game is non-canon, so this is not an reliable element regarding his appearance.

Otherwise, the main antagonist is the Evil Serious Sam Clone, although NETRISCA's entries constantly mention that Mental has been involved with the new and old creatures Sam faces in the game.

Serious Sam 2[]

When Sam is warped to the last of the Sirians' home, he is informed that Mental has one large weakness; a medallion. However, the parts have been scattered throughout the galaxy in order to prevent anyone from using it against him. Armed with this knowledge, Sam sets out to get each of the pieces and remake the medallion.

After clearing out Mental's forces from several planets, he finally makes the Medallion and intends to use it on Mental. Sam managed to pierce the defense shield on Sirius just long enough to enter Sirius, where he did battle against Mental's forces on his home turf. After many battles on Sirius, Sam managed to find Mental's base, the Mental Institution. After fighting off many enemies, including the base itself, Sam finally managed to get to Mental and finish him off once and for all. However, little did Sam know that Mental was already preparing to leave and sent a decoy voicebox in a dark room to distract Sam long enough so that he can escape. By the time Sam discovers the decoy, Mental has already left Sirius and begins heading out to another part of space.

As an end of credits blooper during after Sam retrieves the whole medallion from Ellenier, Sam returned to the Grand Council's home and informed them about having the medallion. While talking to them, he notices a large supply of boxes with individual medallions in the room. Sam learns that the medallion actually did nothing and that there were plenty of them. Angered, he chases the Grand Council around the room wanting some payback.

According to his voicebox, it's hinted that he is Sam's father. It's left ambiguous whether this is true, or a joke about Star Wars made up to distract Sam.

Serious Sam: Double D[]

According to Sam and NETRISCA at the start of the game, Mental has been defeated. However, after exploring Ancient Egypt again, NETRISCA starts to see that something strange is happening, as Mental's forces and crystal beacons made by him have been found. More crystal beacons and monsters are found in two other time periods, suggesting that Mental is still planning to wipe out intelligent life. By the end of the game, it is highly suggested that Mental is still alive and that Sam's fight with Mental was actually him vacationing and turning off NETRISCA during it. The presence of one of Mental's generals, General Maxilla, suggests that Mental is still active.

Serious Sam: The Random Encounter[]

Humans are getting tired of hunting down Mental in the past, so they send Sam Stone and a few pals of his to kill Mental in the future. However, Mental appears to be aware of this, as he sends hordes of monsters towards them, and tricks Sam and friends to enter a large pyramid, where Ugh-Zan is waiting to kill them after solving a switch puzzle in it. After killing Ugh-Zan, Sam and friends strike a cool pose and return to the present, disappointed that Mental was not in the future. Where and when he is, is never told.

Serious Sam 3: BFE[]

By the time Serious Sam 3: BFE has started, it is clear that humanity has lost. Mental sent wave after wave of his forces at the humans, wiping out their extraterrestrial colonies until Earth was humanity's last stronghold. During the war on Earth, many cities, such as Cairo, have become abandoned, indicating that the war took many human casualties. It seems that all that is left is a small group of Earth Defense Force soldiers posted somewhat in Egypt. The humans have placed their last hope on the Time-Lock, which is something that Mental seemed to be unaware of.

During Serious Sam's journey to power up the Time-Lock, Mental stages a final attack on the Earth Defense Force's headquarters, which effectively wipes them out. Now that the last bit of resistance is all but gone, Mental prepares to drop the Moon towards Earth in order to blow the planet up. Sam, however, fights his way towards the Time-Lock, hoping to get in there to give humanity one last chance. Mental attempts to stall Sam long enough so that he can be crushed by the Moon by sending in large amounts of his army and even Ugh-Zan IV, one of his trusted subordinates, but Sam manages to defeat them. As Sam heads towards the Time-Lock, he decides to give Mental a call and threaten him, but instead, Judy Mental, his daughter, answers his call. She tells Sam that her dad is about to "moon" the Earth at any moment. Right afterwards, Sam sees the Moon hurtling towards the Earth, so he makes his way to Time-Lock as quick as he can, right before the Moon hits and obliterates the Earth. In this timeline, Mental manages to finish off humanity, just like all the other species that encountered him.

Serious Sam VR: The Last Hope[]

Set before the events of Serious Sam 3, the Mental War has only just begun. It turns out that not only did Mental target Earth and human settlements elsewhere, but also other planets with intelligent life on them, such as Pladeon and Shaanti. On the planet Shaanti, Mental advances his plans even further by conducting tests on a new superweapon. Sam receives a report from the EDF about this new threat, and destroys it before Mental can use the weapon for his own evil purposes.

Serious Sam's Bogus Detour[]

Set during the events of Serious Sam: The First Encounter, Sam learns that Mental has forged an alliance with a planetary mining company known as the Altani Corporation. The company's success had caught Mental's attention, and became allies with them.

As part of Mental's plan to wipe out intelligent life from the universe, he would have Mental-Altani set up various military bases and outposts of any planet that harbored sentient life, including Earth. Then, he would have them experiment on the planet's flora and fauna with the ooze, wrecking havoc on the planet's biosystems.

Behind the scenes[]

  • Mental was the final boss of the original Serious Sam prototype before it was reworked into The First Encounter and Serious Sam 2.[3]
  • Leftover files in the SDK hints that Mental was supposed to be a brain in a jar with tubes connecting to it.
  • The First Encounter Croteam Bighead model was repurposed from a prototype version of Mental with their faces edited onto Mental's head and the Alpha Sam texture edited onto his body.
  • In the game files of the classic First Encounter and Second Encounter, the Bighead's model is referred to as "Mental". The name "Bighead" first appeared in Serious Sam HD: The First Encounter's game files.
  • There are two unused animations for the First Encounter Croteam Bighead model that shows the creature floating in a bowl and jumping out of it. It is likely that these are a remnant from when this model was used as Mental during development. Cutting off Mental's oxygen supply appeared to play a role during the battle.
  • In one of the original drafts for Serious Sam, Mental was the only survivor of the ancient Neurons Civilization along with his brother who was more powerful than him.[4]



Serious Sam: Next Encounter[]

Serious Sam: Tormental[]

List of appearances[]