|Former Members|| Hydro-Man|
- Hydro-Man: Morris Bench was in the Navy when an accident turned him into living water. He can change into and control any water nearby. Following the defeat of the team, he died in a battle against Spider-Man.
- Medusa: An Inhuman who suffered amnesia. Recruited by Wizard, she reluctantly joined the team. The defeat of the team lead the Fantastic Four to learn of her origins and return her memories.
- Trapster: He uses advanced weaponry.
- Wizard: The leader of the team, he uses his advanced intellect and technology to fight against his foes.
The Frightful Four came together under unknown circumstances by Wizard for the purpose of defeating Reed Richards. They ambushed Thing and brainwashed him to leading the Fantastic Four into a trap. However they were easily defeated by the Fantastic Four, and Thing broke free from their control.
Based on the original group of the team, except for the replacement of Hydro-Man for Sandman. Sandman was intended to be used in a live-action film at the time and not allowed to be used in animation, the reason he was excluded from Spider-Man. Hydro-Man didn't join until later.