While in the womb, Cassandra was diagnosed with myasthenia gravis, an incurable degenerative neuromuscular disease. Her mother, Constance Webb, sought to use the healing properties of spiders found in Peru. In the final weeks of her pregnancy, her mother's security guard Ezekiel Sims betrayed her and stole her research for his own gain, and in a confrontation he shot her. Before she could die, she was found by a tribe of spider-people known as "Las Arañas". Their leader, Santiago, provided a spider to bite her mother and preserved Cassandra's life.^[1]

As she grew up, Cassandra resented her mother for risking her life while she was pregnant, unbeknownst to her that her mother was trying to save her.^[1]

• Precognition

• Cassie Web was portrayed by Dakota Johnson in Madame Web.
  • Holly Dowell and Amanda Bradley were stunt doubles for Dakota Johnson in the role of Madame Web.

• Cassie likes Chinese food.^[1]