Scarlet Witch is a mutant superheroine in the Marvel Comics universe. Created by Stan Lee and Jack Kirby, she first appeared in X-Men #4 (1963).

She possessed the power to affect probability fields. By a combination of gestures and mental concentration she creates a hex-sphere, a finite pocket of reality-disrupting quasi-psionic force, which upon reaching its intended target causes disturbance in the molecular-level probability field surrounding the target. Thus, unlikely phenomena will occur. Among the many phenomena she is able to cause are: the sudden melting of gun barrels, the spontaneous combustion of any flammable object, the rapid rust or decay of various organic and inorganic materials, the poltergeist-like deflection of an object in flight, the sudden evacuation of air from a given volume, the disruption of energy transmissions and fields, and so on. These phenomena occur practically instantaneously after the completion of her hex. Her range of hex-casting is limited by her line of sight (she cannot watch a live television broadcast and cause a hex-phenomenon to occur at its point of origin).

Scarlet Witch's hex-casting ability still has a 20% unreliability factor. Her sorcerous training has not given her a set of powers separate from her mutant abilities, but only honed her control over her existing abilities. She has, however, a special affinity for the natural elements and materials that true witches utilize in their spells: the four classical elements, wood, organic substances, etc. The reliability factor of her hex-casting ability is also limited by her physical condition: when well rested, in good health, and mentally and emotionally alert, Scarlet Witch can cast numerous hex-spheres in rapid succession and attain desirable results for almost an hour. Contrary to certain accounts, the Scarlet Witch cannot levitate, shoot magical energy concussive blasts, or transmute elements.

She is the twin sister of the speedster Quicksilver and, unknowingly, Magneto's daughter. She is also a member of Marvel's premier team, the Avengers and married to the android the Vision.