Nagaina is a female black cobra and is one the main antagonists of Rudyard Kipling's story, Rikki-Tikki-Tavi, and the animated short based off it.
Nagaina was the wife of Nag and an enemy of Rikki-Tikki-Tavi the mongoose. The pair terrorized a Britsh family's garden in India and were often at odds with Rikki-Tikki, the family's pet. When Nag was killed by Rikki-Tikki, Nagaina swore revenge but thought that the man and his gun were the cause of her husband's death. She approached the family while they were having tea, and was about to kill them when Rikki-Tikki showed up, one of Nagaina's eggs in his mouth. He had already crushed all of her other eggs. She turned on him and stole the egg back. Rikki-Tikki chased her down into her hole and killed her there.