In The Matrix (1999), Neo takes the red pill to learn the truth.
Morpheus offers Neo a choice between a blue pill and a red pill. The blue pill would return him to an ordinary version of his life, while the red pill reveals the nature of the simulated reality controlled by the machines. Neo chooses the red pill and awakens outside the Matrix.
The scene became one of the film’s most recognizable images and gave “red pill” a lasting place in popular culture. In the film itself, the choice is about knowledge and reality rather than a simple medicine or a superpower.
The Matrix was written and directed by Lana and Lilly Wachowski, then credited as the Wachowski Brothers. It was released in 1999 and became especially influential for its combination of science fiction, martial arts, and stylized action.