Adversaries

Real name: Victor Von Doom
Powers: master of technology, sorcery, possessing surpeme intelligence, and sometimes the ability to exchange minds with other people too
Place of birth: Haasenstatdt, now known as Doomstadt, Latveria
Base of operations: Latveria

The most dangerous foe of the FF, Doom began as a citizen of the fictional European country of Latveria, an orphan raised in a Gypsy community in his country. Over the years, he took to studying science and even mysticism, and his academic pursuits eventually paid off with getting a full scholarship at the Empire State University in New York. When studying there, that was where he first met both Reed Richards and Ben Grimm, for whom he would later become archnemesis. Richards, in particular, represented a substantial threat to Doom's self-perceived superiority. Consequently, the two scientists became bitter rivals, with Doom moving to another living quarters at the university, and continuing to pursue his goals quite vainly.

Doom's downfall proved to be his vainess and self-centeredness, which prevented him from adjusting the schematics to one of his inventions: a trans-dimensional projection device. The machine worked perfectly...for two minutes, 37 seconds. Then, Doom experienced the end result of his pride: an explosion that scarred his face for life. Although Richards previously had pointed out his classmate's miscalculations, Doom refused to acknowledge his own culpability in the matter. Instead, he blamed Richards for the accident. It was easier for Doom to believe that Richards sabotaged his work out of jealousy than admit to his own imperfection.

After being expelled from the university, Doom traveled the world swathed in bandages -- a kind of living mummy, searching for a miracle cure for his condition, and learning more about the many elements that form the earth, and even sorcery as well. Eventually, Doom discovered a village of Tibetan monks who crafted him a suit of body armor that concealed his deformity. He then returned to his homeland, Latveria, overthrowing the standing government and crowning himself the sole king and dictator of the country. Ruling with an iron fist and an equally strong will, Doom began to redirect the small nation's resources to help him realize his designs of world domination. Doom's life has been shaped by three objectives: the destruction of his hated rival, Reed Richards, world domination, and the liberation of his mother's soul from the demon Mephisto's realm.
Real name: Philip Masters
Powers: talent in electronics, alchemy, and chemistry
Birthplace: Europe
Base of operations: various

Philip Masters was a brillaint but jealous scientist, holding a bitter grudge against fellow scientific researcher Jacob Reiss, who, like him, was also experimenting with special forms of clay. Trying to sabotage Reiss' business, Masters was interrupted by his rival when he came into his laboratory unexpectedly. A fight ensued between the two, resulting in Philip knocking Jacob against a vat of experimental clay, which caused an explosion that blinded Reiss' young daughter Alicia, who was also in the lab at the time. Feeling guilty about what he'd led to, Phillip went on to marry Jacob's widow and adopted Alicia in hopes of helping her and fixing the damage he'd caused, though the marriage itself ended with Marcia's death several years later. Having just Alicia, Masters continued to work on his clay experiments in hopes of finding a cure to his step daughter's blindness. He also learned how to practice alchemy, and discovered that by sculpting a person's likeness from the clay that he could control the specific persons. He tried to control the Fantastic Four a couple of times, but failed and went straight for a while. After a near death experience caused by the Silver Surfer, Masters return to his criminal ways for a time.

He's sometimes considered Ben an ideal soul mate for Alicia, and wanting to help her find happiness in her life, sometimes tried to pair her up with Ben, though his intentions have usually been better than how he's executed them: he once stupidly "made a deal with the devil" by helping Doctor Doom to capture the Four so he could then transfer their minds into little clones of themselves (see 1981's "Terror in a Tiny Town/If this be Doomsday!"), but was betrayed when Doom made sure he couldn't transfer his own mind back into his own body (he'd made a clone of himself as well for play-acting in), but Philip succeeded in exacting revenge by reprogramming the robot residents of the town, sabotaging Doom's attempt at transferring his mind back to his own body as well (he'd made a robotic body for himself to dwell in), and while he didn't manage to actually capture him, he certainly managed to use the robots to chase Doom out of his mansion.

One of the things that makes Masters work as a character is that, even as a crook, he's still got a redeeming side to himself, and can do good things as well as bad.

Later on, Masters became the controller of a small town in Florida under special immunity by the government, where he specialized in controlling criminals in the witness protection program to fly straight.
Real name: Anatha Na-Mut
Powers: Above normal intelligence, superhuman strength, agility and reflexes, demi-godlike stamina and durability, peak human speed
Birthplace: Egypt
Base of operations: usually Egypt

The Sphinx was a wizard in an ancient Egyptian pharaoh's court, dismissed after his sorcery began to fail, which displeased his boss. He then set off to plot ways to become a world conquestor over the centuries, improving his abilities and powers, and it was his discovery of the Ka Stone that enabled him to come to power. He first appeared in Nova, starring a minor character by that name, and went on to menace various other notable characters in the MCU as well, including the Fantastic Four and Ben himself, and even Doctor Strange, the New Warriors and even the Thunderbolts.

At one point, after being defeated by Galactus, the space-bred warlord shattered his Ka Stone into dust, scattering it across the Egyptian desert, and then sent him into a time-loop, where he ended up reliving his own same history repeatedly. But in doing so, Na-Mut found a way to undo the trap in which Galactus had stuck him, and managed to emerge from the effects, plotting to resume his conquesting ways again. It was Ben's intervention that helped to prevent him from fully succeeding in reassembling the Ka Stone, which he had hoped to do, though he did manage to restore part of it, upon which he decided to take off in his own ship-base before Ben could get a chance to stop him again. He would return later on to try and lash at Ben again, and was seemingly killed when the Ka Stone was crushed. But he survived, and later on fought Doctor Strange, in a storyline in Doctor Strange #27 vol 2, in which it was revealed that he was a mutant, not unlike Apocalypse, one of the X-Men's most notable adversaries.

In the New Warriors, another Sphinx whose name was Meret Karim, also from Egypt, got merged with him. And in the Thunderbolts, he tried to take possesion of a Kree Stone to use for his crooked deeds.
Real name: unknown
Powers: Born with an extraordinary talent (not a superpower) called photographic reflexes and/or a camera-like memory. How this talent works is by having him watch a skilled fighter, do his or her moves and because of this, his body will automatically know how to do those moves without practice, no matter how complex. This ability is only limited due to the fact that he has no authentic metaphysical super powers.
Birthplace: Bronx, New York
Base of operations: various

The Taskmaster, whose exact background is shrouded in secrecy, was born with an extraordinary ability to mimic all sorts of fighting styles from martial artists, archers, gunmen, acrobats, etc, a talent he first displayed when watching a martial arts movie on television when he was young. He's gathered a large variety of skills from paying attention to only so many of the best crimefighters in the Marvel Universe, including Captain America, Hawkeye, Black Widow, Spider-Man, Black Cat, Ant-Man, Iron Man, and so on. He's often ran his own training centers for other mercenary wannabes, and during the mid-80s was running a training ground at a circus in Ohio, where young Vance Astrovik unwittingly joined up with his circus when he was fleeing from home, and then teamed up with the Thing to put a stop to the Taskmaster's crooked activities there.

He's long led a career as a ruthless mercenary, and once tried to take out Iron Man's alter ego, Tony Stark, but was foiled in his plans. One of the most clever things about him is how he tends to be quite a "slang-talker" at times.

An interesting aside about the Taskmaster is that he may have been meant as a comment on kids who watch too much television at home. Which is certainly an intriguing theory IMO, to say the least.