The Fantastic Four's Invisible Woman, Susan Storm, is one of the few Marvel characters who has singlehandedly killed a Celestial, one of the almighty space gods who can destroy entire planets on a whim. Susan is commonly recognized as the most powerful member of the Fantastic Four, but this feat proves she is also Marvel Comics' strongest hero.
Susan Storm began her career as the weakest member of the Fantastic Four. The ability to turn invisible paled in comparison to her brother Johnny's fiery power, Ben Grimm's strength and resistance, and even Reed's stretching abilities. Pretty soon, however (starting with Fantastic Four vol. 1 #22), she realized she could also project and manipulate powerful force fields that are incredibly resilient and malleable. Even this awesome power, however, pales in comparison to the Celestials, cosmic beings as old as the Multiverse that cannot be hurt by mortals and overpower even the gods. Even mighty heroes such as Thor and the Sentry could barely leave a scratch on them, but Susan Storm did much more than that.
In Fantastic Four vol.1 #400 by Tom DeFalco, Paul Ryan, John Kalisz, and Scott Marshall, the team (missing Reed Richards, who is replaced by Kristoff, Doctor Doom's adoptive son) finds itself in the middle of a conflict between the Watchers and the Celestials. The Fantastic Four, trying to help their friend Uatu, go against the Celestials, but they are unable to penetrate their armor. Nathaniel Richards, Mr. Fantastic's father, theorizes that the only one who can do that is Susan because the energy of her forcefields comes from "hyperspace," which is the Celestial's place of origin. Susan is able to break through the armor of Exitar the Exterminator and enters the giant body of the Celestial. After reaching its brain, she destroys its nerve center, making Exitar disappear.
Susan's feat is nothing short of astounding. The Celestials' armor has resisted the combined might of the Asgardian gods channeled through the Destroyer armor, the power of three Skyfathers together, and even the Ultimate Nullifier. Surely, Susan's powers having the same origins as the Celestials is a unique weapon in her arsenal, but this takes nothing away from the fact the Invisible Woman managed to succeed where even the gods failed. Her ability to project forcefields is only limited by her own willpower, as Hyperspace is a source of infinite energy, which means Invisible Woman's powers are the perfect counter to those of the Celestials, who also draw from the same limitless source. Susan's kind and caring personality makes her use her powers in a mostly defensive way, but her forcefields can be one of the most powerful weapons in the Marvel Universe, as she proved when her evil personality, Malice, took over her body and was almost unstoppable.
The Invisible Woman rarely gets the credit she deserves and is often overshadowed by the louder personality of Johnny and Ben, or by Reed's scientific genius. The truth is that, in of pure powers, Susan is one of the strongest heroes in the Marvel Universe. Her connection to Hyperspace also makes the Invisible Woman of the Fantastic Four the only person capable of hurting, or even killing, a Celestial (with the exception of vampires) a feat that no other Marvel hero can replicate.
