Kaa is the secondary antagonist of Disney's The Jungle Book and its 2003 sequel The Jungle Book 2.
The Jungle Book
Kaa comes across Mowgli and Bagheera in the branches of a large tree that the pair have chosen to spend the night in. As Bagheera is nearly asleep, he is unaware of Kaa as he investigates Mowgli. Annoyed, Mowgli angrily tells Kaa to leave him alone. Bagheera sleepily orders Mowgli to go to sleep, as he has assumed Mowgli was speaking to him. Kaa decides to take advantage of the situation, and hypnotizes Mowgli, wrapping the boy in his coils, with the intent of devouring him. During the hypnosis and coiling, Mowgli tries to call for help, but is silenced when Kaa wraps and tightens Mowgli's neck with his tail and then squeezes the boy with all his coils, from legs to neck. But Mowgli's struggles awaken Bagheera, and he is able to rescue Mowgli by hitting Kaa in the face just before Mowgli is eaten. However, Kaa is angered by the interference, and begins to hypnotize Bagheera. By now, the coils around Mowgli unravel and he has awakened, and he shoves Kaa's massive coils off the branch, resulting in Kaa falling to the ground in a heap. While Mowgli awakens Bagheera by slapping him, Kaa begins to slither off, swearing revenge. However, his slithering is inhibited by a knot in his tail, which Mowgli laughs at.
Kaa later reappears coming across the now bitter Mowgli, who is lost in the jungle. He tries to hypnotize Mowgli again, who has learned from his last encounter and is wary of the snake. Mowgli tries to leave, with the response that he doesn't trust anyone. However, Kaa uses the boy's desire to stay in the jungle as a means of gaining his trust. Kaa is able to hypnotize Mowgli again and sleepwalk him into his coils while singing the song "Trust in Me".
But before Kaa can devour Mowgli, Shere Khan stops by after hearing Kaa's singing. As Shere Khan is looking for Mowgli, Kaa is forced to hide the boy. Kaa is able to trick Shere Khan into believing that Mowgli is nowhere in the area, despite Shere Khan choosing to inspect Kaa's coils. Shere Khan walks off to continue the search, leaving Kaa safe to admit his disgust for the tiger. When Kaa shivers after seeing the tiger walk off, his coils unravel like before and Mowgli awakens. Kaa takes a moment to pity the helpless Mowgli, but reverts once he remembers his own intentions. At that point, Mowgli is able to push Kaa's coils to the ground. On the ground, Mowgli confronts Kaa and accuses the python of lying, which he wasn't. Kaa, assuring Mowgli that he indeed can't trust anyone, moves in to attack, but is once again stopped by a knot in his tail. Seeing Mowgli run off, Kaa apparently gives up trying to catch him as he slithers off again.
The Jungle Book 2
Kaa returned once again as the secondary antagonist and plays a relatively smaller role in the sequel than he did in the 1967 film. One night, Kaa appears when Mowgli meets up with Baloo near the beginning of the film. Like before, Kaa attempts to eat Mowgli, but faces many accidents and injuries as he pursues them. Mowgli and Baloo remain unaware of Kaa's presence, and the two walk away unharmed.
Kaa angrily states that he never wants to see another Man-Cub again, but changes his mind after he comes across Shanti. Kaa manages to corner and hypnotize the young girl. Before he can eat her, Shanti is saved by Ranjan, who pulls Shanti out of the way, beats up Kaa with a large stick which resulted in him swallowing down a large rock which Shanti was standing in and sends him sliding down a cliff to a coconut tree after Ranjan scares him. He is then encountered by Shere Khan in his search for Mowgli; Khan believes that Kaa knows about Mowgli's whereabouts (after hearing him say "man-cub"), but truthfully, Kaa has no idea where Mowgli is; but Shere Khan won't believe him and continues to threaten the python. To stop angering Khan, Kaa fearfully lies to the tiger that Mowgli is at the swamp, allowing him to flee. He isn't seen again for the rest of the film but is mentioned by Shere Khan when he arrives at the swamp where Mowgli is nowhere to be seen and angrily splashes the water saying "That snake lied to me!".