"Charly" (1968) film with Cliff Robertson in the titular role, was inspired by a science fiction short story "Flowers for Algernon." Charly had an IQ of 69 & was working as a janitor in a bakery. On undergoing a brain surgery, his IQ triples & his life undergoes a change also. But unfortunately it proves short-lived & after a few months, he regresses to his former self. Music for this film was provided by Ravi Shankar.
"Rainman" (1988) starring Dustin Hoffman tells the story of a man, heir to a fortune, institutionalised with an IQ of 87. After his father's death, his selfish greedy brother kidnaps him & accidentally discovers that he can gamble successfully. Meanwhile the asylum doctor arrives & claims custody. Initially opposing the asylum's claim, the selfish brother has a change of heart & accepts the "Rainman" as only his brother.
"Forrest Gump" (1994) memorably played by Tom Hanks, had an IQ of 75 & was rejected by the Army. But unfazed, he engages himself in various enterprises, succeeding in all of them. While doing so, he also gets involved in various key events in 20th century American events. The film ends happily with Forrest proudly seeing his son off on his first day at school.