Perhaps the most enduring member of that long-gone Age of Monsters, Fin Fang Foom is also the most complex and intriguing. Piecing together this monstrosity's history is patchwork at best, and often somewhat contradictory. Ulysses mentioned an encounter with the beast once, but refused to go into details, simply stating that the story would be told when it was finished between the two. Using correspondence from Dr. Chen Liuchow (the gentleman who first unleashed the ancient dragon upon the modern world), the very reliable Reed Richards, and the Avenger known as Iron Man, here is what I have pieced together for Elsa's project.
According to Iron Man, the creature once thought to be native of China's Valley of the Sleeping Dragon was actually the navigator of a starship from a planet called Kakaranathara (though Iron Man notes this world is sometimes referred to as Maklu IV). Theirs was a race of peace, but the alien we know as Fin Fang Foom - meaning "He whose limbs shatter mountains and whose back scrapes the sun" - and a group of dissidents escaped, setting out to conquer other worlds. Arriving at some point in what we now consider ancient China, Foom and his cohorts were confronted by a group of natives, and a member of the dragon's crew was slain. The rest, not ready to start their conquest (please keep in mind that these Kakaranatharians were apparently young for their race and not yet fully grown to the roughly 32-foot length we associate with Fin Fang Foom), used their natural shape-shifting powers to mimic human forms and blended into this new world, biding their time. That is except for Fin Fang Foom. Wishing to keep a sort of "back-up" in hiding in case the rest of the crew failed or were killed (as at least two more were over time), Foom was placed in a well-hidden tomb and given a potent herb that placed him into a long slumber.
As his other would be conquerors slipped into domestic lives, Foom slept for most of the next few centuries, but awoke at least once during the 8th century. Again, the details are murky, and much of it is just the stuff of local Chinese legend, now, but somehow, the herb was used to place the now grown dragon back to sleep. A cult like group of humans began to guard the entrance to his lair, with their descendants taking up the mission as time went by.
The Sleeping Dragon rested for centuries until sometime in 1961, when teenager Chan Liuchow found some manuscripts describing the legend of Fin Fang Foom. At that time, Liuchow's homeland was being terrorized by the communist Chinese, and wishing to find his own unique way to stop the invaders, Chan investigated to see if the legends were true. Finding the slumbering giant, Liuchow awakened him and, taunting him, led the behemoth straight into the communist camps, decimating them. With his plan accomplished, Liuchow lured Fin Fang Foom back into his tomb, using the herb to place the creature to sleep once again.
Humanity probably hoped it had seen the last of this intelligent, speaking leviathan, but alas, it was not to be. A bizarre man named the Collector found the sleeping creature and captured it for his collection of giant monsters. When our old annoyance Harvey Rupert Elder, now the Mole Man, invaded the Collector's lair, Fin Fang Foom was set loose again alongside many other giant monsters. While many monsters rampaged through New York City after this debacle (please see my notes on Groot, Rommbu and other), Fin Fang Foom headed elswhere, but was still felled by the-new Fantastic Four. With nowhere else to contain the beast, the adventurers exiled the dragon to Monster Isle.
At some point, with no real security measures to hold him, Foom returned to his old Chinese tomb and once more fell asleep. Shortly after, though the villainous madman Dr. Vault mentally controlled the dragon, targeting it the Living Colossus. Resisting Vault's command, (for reasons of his own) aided It against the invading extraterrestrial Stonians, the brethren of Gorgolla. After this new threat was driven off, Vault briefly regained control and the two allies did indeed clash, with Fin Fang Foom employing martial arts against its stony opponent. Shaking the remnants of Vault's influence though, Fin Fang Foom directed it to Vault, and returned to his lair once more.
By all accounts, Fin Fang Foom spent several years in quiet slumber, broken again when a cult calling itself the Beyond Reason Spiritual Fellowship used his as a vessel for their demonic lord, Aan Taanu. Chan Liuchow, now a middle-age doctor, aided a group of supernatural beings known as Legion of Night against both Foom and the cult. When Aan Taanu was driven from this reality, Foom, confused by his sudden awakening in the middle of New York City, escaped back to his lair.
A short time later, the super-villain known as the Mandarin (whose rings of power were actually artifacts from Foom's spaceship) found in the Valley of the Sleeping Dragon, having been directed there by the Makluan starship captain, who had taken the human identity of Chen Hsu. Awakening Fin Fang Foom (who was now over one hundred feet tall), Mandarin used him to threaten the Chinese government. The Chinese called in Iron Man to confront them, but he was quickly defeated. Another Iron Man arrived to help, but at this point, the rest of Foom's crew decided to shed their mortal shells and revealed themselves to the world. Foom and nearly a dozen of his cohorts terrorized the Chinese before the two Iron Men along with the Mandarin - who realized the aliens were merely using him - combined the energies of Iron Man's armor and the Mandarin's rings into a small nuclear blast that was thought to have wiped out the dragons.
This was not the end of Fin Fang Foom, though. As best as Iron Man could figure out, his spirit inhabited a small artifact of a dragon, which in turn possessed the body of young Billy Yuan. Using Yuan as a vessel of sorts, Foom began to change Billy's form into one more closely resembling his own. Battling Iron Man again,Foom called upon literally thousands of lizards residing in the sewers to merge with his body, restoring him to his full size and power. Even fully reborn, he proved no match for the Avengers, who defeated him yet again. Iron Man was forced to place Foom into custody of Sunset Bain of Baintronics, but due to various legal decisions, he was again relocated to Monster Isle among other creatures of similar power and size. After battling a league of heroes from another dimension who had come to Monster Isle to obtain the Ultimate Nullifier, Fin Fang Foom went on to face the Avenger Thor, and was slain by him in battle. Thor took custody of the creature's skeleton, but even this could not keep the dragon's restless spirit incapacitated. However, Foom began to rethink his role in the world, and became a follower of Buddhism.
With the rest of his space crew gone, Foom reformed both physically and mentally, agreeing to a program established by Reed Richards to rehabilitate monsters and bring them into society. Along with several other creatures (see my notes on Googam, Gorgilla and the robot Elektro), the once mighty dragon was reduced to human size and hypnotically striped of his powers. Once this was accomplished, he was hired as head chef of a Chinese restaurant within the Baxter Building.
The former would-be world conqueror now seems mostly content to boss around his waiters. Recently, though, Foom and his fellow "reformed" monsters made headlines for stopping an invasion from another dimension by the creature known as Tim Boo Ba. Whether or not Fin Fang Foom has truly reformed remains to be seen, but for now, at least he is under the watchful eye of the Fantastic Four. Be advised, however, that his former captain Chen Hsu has been reported as having survived, so his comrades may yet come to reclaim him.
Also, for the record, it must be noted that Thor's nemesis the Midgard Serpent once used Foom's likeness (only with orange scales instead of green) to conceal its true identity from Thor.
Note: This information comes from the files of Ulysses Bloodstone (and the Monster Hunters).