In the story Rikki-Tikki-Tavi by Rudyard Kipling, the antagonist is Nagaina, a cobra. She is the wife of Nag, another cobra, and together they pose a significant threat to the family and the garden animals. Nagaina is cunning, aggressive, and determined to protect her eggs and eliminate any threats to her family, including Rikki-Tikki-Tavi, the mongoose protagonist.
Nagaina’s actions drive much of the conflict in the story. She plots to kill the human family to ensure her eggs’ safety and tries to deceive Rikki-Tikki-Tavi to gain an advantage. Her relentless pursuit of her goals makes her a formidable adversary for Rikki-Tikki-Tavi, who must outsmart her to protect the family and maintain the balance in the garden.