I've come to save you.
Xemnu's the first and original being to be nicknamed "Hulk" first appearing in the Golden Age of Marvel, where it focused not just on comic heroes, but also other stuff like horror. In particular, Jack Kirby's long running Journey Into Mystery title brought a unique spin on the genre, showcasing normal everyday people having to deal with interplanetary creatures, demons, and other abominations from beyond. In this world, there were no such thing as super-heroes, and the day was usually only saved by lucky chance or the ingenuity of people getting one over the beast.
Xemnu was one of the first to be brought into the Marvel universe, fighting with Hulk multiple times and becoming a occasional villain with other heroes....mostly just Hulk through.
At the moment, Xemnu's getting his big spotlight in Immortal Hulk, so I figured that it would be the perfect time to go over all of his feats, and also use this in future when his other feats are showcased, cuz his arc isn't finished yet.
Scan 1/2- Xemnu when destroyed can just turn into a bunch of mist and take over other bodies, eventually transforming them INTO him, through we don't see this transformation on panel, he turns the human body of a average astronaut and makes him into his own body. (Marvel Feature #3)
Scan 1/2- Xemnu can turn humans into mechanical creatures like himself through a process of nourishment: while feeding on them, he turns them into lifeless organic robots. (Immortal Hulk #33)
Scan 3- Xemnu quickly does this to the Minotaur (Dario Agger) overpowering him in the process.
Stats and info on the character. (Official Handbook of the Marvel Universe Update 89 #8)
Updated listing and da Power Grid (in particular, it is shown that Xemnu's mist form is FTL in speed) (Official Handbook of the Marvel Universe Update #1)
Scan 1/2- A magical blast from Doctor Strange only stuns Xemnu for a moment, he quickly adapts and creates a shield to block him. (Marvel Feature #3)
Scan 1- A person with Xemnu's body is trapped in molten slag and flames from Firebird but is unharmed and smashes out of it. (Beyond #4)
Scan 2- As shown, the shattering is so violent that the pieces fly fast enough to hurt people and require multiple heroes to defend against it
Scan 1/2- Despite being smacked around by She Hulk with a sucker punch, Xemnu quickly recovers and knocks her out. (Sensational She-Hulk #7)
Falling from outside the Earth's atmosphere only makes him unconscious (Journey into Mystery #62)
Tanks multiple blows from a hydrated Namor and one shots him with a mental bolt. (Marvel Feature #3)
The Hood's magic bullets bounce off him harmlessly (Beyond #4)
Scan 1/2/3- Casually overpowers Medusa's hair and throws her into orbit from Battleworld (Beyond #4)
Causes the earth to quake and spilt open with a fist (Beyond #4)
Crushes a man in his hand and kills him. (Marvel Feature #3)
Crushes Deathlok in his hand, making him scream in pain (while no selling Firebird) (Beyond #4)
His physical power is described as almost limitless (Journey into Mystery #62)
Hurts She-Hulk with a uppercut. (The Sensational She-Hulk #43)
Lifts a massive amount of rubble over his head (possibly a entire building worth based on how small the people look compared to it) (Beyond #4)
While weakened, it is able to lift a entire theatre off its foundations (Journey into Mystery #66)
Builds a device that can convert babies into members of his own race. (Sensational She-Hulk #7)
In the same issue, Xemnu also pulls out a identical device which only works on super-human beings (Sensational She-Hulk #7)
Builds a high tech spacecraft on Earth using resources available to him. (Marvel Two In One #78)
Scan 1/2/3- Designs Kluh, a intellectual Hulk made out of Banner's genes that is able to beat down Composite Hulk (Red Hulk and Hulk fused together) for a bit and send him flying above the clouds. (Hulk #30)
Scan 1- Successfully clones five creatures of different powers, these being Blip, Diablo, Goom, Groot and Taboo, all Golden Age monsters. (Incredible Hulk Annual 1976)
Scan 2- These clones were also specifically designed to drain Hulk's Gamma energy bit by bit through a long gauntlet match, eventually making him weakened enough to be captured. In a way, Hulk did Knightfall before Batman did, lol.
To recover, Xemnu has people build him a energy reflector to absorb energy from stars, allowing him to become stronger. (Journey into Mystery #66)
Scan 1/2/3- Using tech to create and train new lifeforms, Xemnu creates a army of monsters that not even the Hulk seems to be able to fight back against (Hulk #30)
Scan 1/2- Attacks Savage Hulk with trees and rocks (Defenders #12))
Contains multiple gamma mutants inside bubbles (these same gamma mutants were ripping people and even the Hulk apart) (Immortal Hulk #30)
Morphs a giant barbell around Thing while controlling Wonder Man. (Marvel Two In One #78)
Scan 1- Morphs pipes and a streamroller to attack Strange and Valkyrie. (The Defenders #12)
Scan 2- For some reason Valkyrie can't smash through them, even through she has super strength, lol.
Reanimates a bunch of objects (The Defenders #12)
Reanimates costumes to beat up Thing (Marvel Two In One #78)
Uses a psychic shield to protect himself, thugs controlled by him knock out Doctor Strange just by punching him: which is either a massive low showing or a showcase of how powerful he can make people under his control. (The Defenders #12)
Scan 1/2- Uses his powers from a distance to carry a sleepy Hulk to his lair. (The Incredible Hulk Annual 1976)
With little to no power left, Xemnu drags a asteroid and makes it hit his craft hard enough to send it back to Earth. How much could he do at full power, I wonder.... (Journey into Mystery #66)
Casually uses his powers to control Red Hulk and make him beat himself up. (Hulk #30)
Scan 1/2- Controls kids on the TV on his fantastic show, Astro-Nuts, sells tons of toys of himself (Marvel Feature #3)
Scan 3- Eventually he uses his powers to gather millions to his location.
Scan 1/2- Controls Wonder Man and makes him fight Thing. (Marvel Two in One #78)
Despite his powers being completely disabled via a psionic device, Xemnu is still able to use his powers to influence some alien dude to freeing him (Sensational She-Hulk #43)
Scan 1/2- Despite Hulk's immunity to telepathy, Xemnu's powers put him under intense pain. Strange states that Savage Hulk only survived due to his brain being too small to control, rude smh (Marvel Feature #3)
Scan 1/2- Disguises himself as a human. (Marvel Two in One #78)
Scan 1/2- Easily knocks out She-Hulk, Razorback and a bunch of fodder, making sure everyone on the space station they were at were also unconscious as well. (Sensational She-Hulk #7)
Scan 3- For scale, the space station was easily larger than moons around it.
Scan 1/2- In seconds, Xemnu controls the entire world using his powers and turns them all into his slaves. (Journey into Mystery #62)
Scan 3- This event was so psychically traumatic that everyone forgot about it when Xemnu was defeated bar one dude who was left not controlled cuz Xemnu is a ass and wanted the dude to watch him dominate the Earth
Scan 1/2- Knocks out Savage Hulk with a psi bolt. Hulk was so distressed that he telepathically calls out to Strange for help. (The Defenders #12))
One shots Doctor Strange in a second using his telepathy. (Marvel Feature #3)
Out of the available X-Men, only Colossnaut is mentally immune enough to get through Xemnu's psychic powers (Uncanny X-Men #9)
Scan 1/2/3- Rewrites the memories of the planet so that everyone forgets about Banner Hulk and places himself as the only Hulk to exist. Savage Hulk wasn't effected by this but Devil Hulk was, and completely forgot about who he was. (Immortal Hulk #31)
Scan 4/5- Xemnu even goes to the trouble of individually rewriting memories of everyone so that he was the hero and important to them over whoever was there at first.
Scan 1/2- Manages to hold Savage Hulk within Banner's consciousness, as well as altering Banner's personality, making him more vicious. Through Savage Hulk wasn't effected by Xemnu's memory altercation, he was unable to emerge from Banner's psyche, requiring Green Scar to get through the mental block. (Immortal Hulk #32)
Scan 1/2- This massive psychic act also rewrote decades of established history to replace Hulk with Xemnu, making him a member of the Avengers, X-Men, etc, while Banner was rewritten as a public villain. For this to have been successfully done, it would have undoubtedly involved keeping said teams compliant using his powers, so strong feat either way (The Immortal Hulk #32)
Scan 1/2- Even the Green Scar personality can't pull Banner's mind from Xemnu's, despite his impressive resistance feats against telepathic attacks in the past (taking Xavier and Emma attacking him at the same time, etc) and Savage Hulk is needed to sever the connection. (Immortal Hulk #33)
Through also from his magic spell being maintained, Doctor Strange (disguised as Hulk) feels uneasy close to Xemnu's presence (Marvel Feature #3)
Scan 1/2/3- Traps Cho Hulk in a detailed illusion. (Totally Awesome Hulk #1)
Scan 4- Xemnu also does this to everyone in Seoul, giving them specialised fantasies.
Scan 1/2- Turns Cho Hulk near savage using his telepathy (Totally Awesome Hulk #1)
Used his powers to block Hulk's mind from communicating with anyone else, effectively overpowering Strange's passive telepathy (The Incredible Hulk Annual 1976)
Uses his powers to prevent Doctor Strange from using any of his magic or any of his arcane knowledge. (The Defenders #12)
Scan 1/2- Uses his powers to slowly sap the strength out of She-Hulk and render her helpless. (Sensational She-Hulk #43)
Scan 1/2- Xemnu as a member of the Select is able to overpower Moondragon, a powerful telepath, and knock her down with one shot. (Annihilation- Conquest #1)
Xemnu is classified as a being with high capability in influencing people according to Norman Osborn's database. (Dark Reign Files #1)
Scan 1/2- Overflows the minds of the world inside the mind of the Savage Hulk, which almost leaves him braindead in the process. (Immortal Hulk #33)
Well, there you have it. Xemnu's a beast with great physical stats, strong telekinetic power, a bunch of strange powers (like his reanimation stuff) telepathy that can drop even Savage Hulk at times, and a ability that allows to live forever through converting other bodies into his own.
In a sense, he really is the Immortal Hulk, lol. Better than that other green guy anyway, idk who he is