The Frightful Four is are a group of fictional antagonists and villains appearing in American comic books published by Marvel Comics. They serve as the antithesis to the Fantastic Four.
When the Sandman and Trapster escaped prison together they rescued a helpless Wizard, adrift due to his malfunctioning anti-gravity discs, along the way. Together they formed an alliance dedicated to humiliating and defeating their mutual enemies, the Fantastic Four, by becoming an evil, mirror counterpart. Determined to form their own quartet, the criminal trio went through a series of brief recruits, none of whom proved satisfactory as a fourth member. Their first choice was an amnesiac Medusa. They were fairly successful at first, almost killing the Fantastic Four and turning the Thing against his team before finally being defeated and put in prison.
Medusa soon deserted them after regaining her memories. Later attempts at a fourth member included Blastaar, a mind-controlled Spider-Man, Thundra, the Brute (an alternate Reed Richards from Counter-Earth), Electro, and Llyra, who took over the group and forced them to attack the Sub-Mariner for her.
After the Sandman turned his back on his criminal ways, the Wizard formed an all-new group with the Constrictor, Deadpool, and the Taskmaster, but they were bested easily by the Thing and Franklin Richards. Wizard next teamed with the Trapster, the Man-Bull, and Dreadknight, but they were defeated by the Turbine, Spider-Man, and the Rangers on a test run in Canada.
More successful was a "Frightful Five" allying the Wizard, Hydro-Man, Klaw, and Titania with Aron the Rogue Watcher. Aron's power defeated the Fantastic Four, but he ultimately seized them for his own ends and banished the Frightful Four to the Vault. Trying to rebuild this nearly-successful team (minus Aron), the Wizard recruited Klaw, who had freed the mutating and embittered Ms. Marvel (Sharon Ventura). With those two and the Red Ghost, who had sought out the team to join, Wizard was beaten yet again by the Fantastic Four, despite the absence of Reed Richards. Klaw and the Red Ghost fled, so the Wizard and Ms. Marvel teamed with Trapster and a reprogrammed Punisher (robotic "watchdog" of Galactus) to fight the Fantastic Four on Wyatt Wingfoot's Keewazi reservation. When the heroic Fantastic Four seemed to be led by Dr. Doom (actually Reed trapped in Doom's armor), Wizard surrendered rather than risk Doom's wrath.
The Wizard's next team was a dysfunctional echo of the Fantastic Four's family structure; including the Wizard's half-dragon, ex-wife Salamandra, and their mass-shifting daughter Cole; as well as Hydro-Man and the Trapster. Wanting to humble the Fantastic Four on equal terms, the Wizard banished the Trapster into a time-loop after he threatened Cole, reducing his team's ranks from five to four. With the rebellious Cole's aid, the Fantastic Four invaded the Wizard's underground headquarters and defeated the Frightful Four, though the team escaped and remains at large.
The Frightful Four has reappeared with Wizard, Hydro-Man, and Trapster being joined by Titania. Planting a listening device on Mister Fantastic's FTL (his latest spaceship) and a bomb, the Frightful Four attacked a solo Invisible Woman on Saturn's moon of Titan and captured her while the Fantastic Four watched from Earth. As they attempted to rocket to her aid in the FTL, the bomb exploded.
The Wizard remade the Frightful Four along with Dr. Malus and Klaw. Both the Wizard and Klaw freed Carnage from prison in hopes to control him into becoming their secret weapon. As Cletus Kasady's brain was lobotomized, The Wizard couldn't control him. He and Klaw subdued Dr. Malus long enough to transfer the symbiote into his more easily controllable brain.
Along with a new "superior" Carnage, the villains attacked the City Hall in order to take over New York, but they found themselves against Spider-Man.