Cassandra Webb (Madame Web) is a clairvoyant and precognitive mutant who first appears to help Spider-Man find a kidnapping victim. She is usually depicted as a supporting character in the Spider-Man comic book series, where she appears as an elderly woman with myasthenia gravis (a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness) connected to a life support system resembling a spiderweb.