Paa (transl. Father) is a 2009 Indian Hindi-language comedy-drama film directed by R. Balki, starring Amitabh Bachchan, Abhishek Bachchan, and Vidya Balan. Jaya Bachchan makes a cameo appearance in the opening credits of the film as a narrator. The film is inspired by the 1996 Hollywood film Jack as per some reports and is based on the relationship of a boy with a rare genetic condition progeria and his parents. Amitabh and Abhishek, father and son in real life, play son and father respectively in the film. The film was released worldwide on 4 December 2009. Veteran composer Ilaiyaraaja scored the film's music.

The film was critically acclaimed in India and fared well at the box office. Despite a warm reception from Indian film critics, the film received mixed reviews from overseas film critics, according to the websites Metacritic and Rotten Tomatoes. Amitabh Bachchan received his third National Film Award for Best Actor at the 57th National Film Awards for his performance and his fifth Filmfare Award for Best Actor and Vidya Balan got her first Filmfare Award for Best Actress.

Auro is an intelligent and witty 12-year-old boy with an extremely rare genetic disorder called progeria. Mentally he is twelve and very normal, but physically he looks five times older. In spite of his condition, Auro is a very happy boy. He lives with his mother, Vidya, who is a gynaecologist. Meanwhile, Amol Arte is a young, flamboyant politician. He is out to prove to the world that "politics" is not a bad word. He is a man with a mission. Auro is Amol's son; however, Vidya conceals this from him. Amol meets Auro when he visits Auro's school as a chief guest of a competition on the "visionary of India." Amol decides Auro is the winner, impressed by the white globe he made. But being seen with such a prominent politician, Auro is found by the media.

The next day, the media tries to enter his school. Auro, annoyed at this, sends him an email, which says, "I hate you." Amol reads it and obtains a restraining order from the High Court stating that nobody can disturb him without permission. Auro, relieved, tells him of his desire to visit the president's house. But due to Amol's political issues, he fails to show up on the appointed day. Auro, however, loses confidence in him but later agrees to go to Delhi with him, although he now knows that Amol is his father. Though Amol does not know that Auro is his son, he takes him to Delhi to see the president's house. Auro says that he still needs to forgive Amol for his first mistake (not accepting him), but he doesn't tell him what it is. On his 13th birthday, he is in the hospital, and he tells his father that he, Auro, is his father's mistake. Auro tries to get his mother and father back together, but Vidya resists, still hurt by the fact that Amol wanted her to have an abortion when they first found out she was pregnant.

Amol realizes his mistake and proposes to Vidya, as he is still in love with her. He stays by Auro's side when he finds out that Auro is his son. Auro's health begins to deteriorate as his aging catch up. However, he is finally able to reunite his mother and father as Vidya gives in to her feelings for Amol and her motherly love for Auro. They perform the first wedding rites in the hospital in front of their dying son, implying that they will do the rest later. Auro says his last words, "Maa," to Vidya and "Paa," to Amol before dying with a satisfied smile. The movie ends in the rain with Vidya mourning Auro's death as Amol comforts her.

The film had Amitabh Bachchan playing the role of a child who is suffering from Progeria, a genetic disorder which leads to the quick acceleration of the ageing process in children. Abhishek Bachchan, Amitabh's real-life son, played the role of his father.

Vidya Balan was the only choice for the mother's role. Arundathi Nag, the wife of late Kannada actor-director Shankar Nag was asked to play the role of Vidya's mother.

Most of the parts were shot in Lucknow and some parts of the film were shot in the UK and Malaysia. A small portion of the filming was done at Cambridge and Oxford. The clock of Corpus Christi College and the courtyard of St. John's College in Cambridge and Brasenose Lane and Radcliffe Square in Oxford have been shown in a song sequence. The film was also shot in Taiping, Malaysia. The King Edward VII school was actually one of the typical Malaysian schools.