Peter Gardner Ostrum (/ˈoʊstrəm/ OH-strəm; born November 1, 1957) is an American retired veterinarian and former child actor, whose only film role was as Charlie Bucket in the 1971 motion picture Willy Wonka & the Chocolate Factory.

Ostrum was 12 years old when selected by talent agents for Willy Wonka. Though he enjoyed the experience of shooting the film, he opted not to sign a three-film contract when it was over. After eschewing a career in film and theater, he was reluctant to speak about his one starring role. In 1990, he began an annual tradition of speaking to schoolchildren about the film, and he became a subject of interest again when the 2005 film Charlie and the Chocolate Factory was released to theaters.

Ostrum became interested in his family's horses when he returned from shooting Willy Wonka and was particularly influenced by the veterinarian who tended to them. Ostrum received a Doctorate of Veterinary Medicine from Cornell University College of Veterinary Medicine in 1984 and retired by late 2023. As of 2021^[update], he lived in Glenfield, New York with his wife Loretta (née Lepkowski), having raised two children.

Peter Gardner Ostrum was born in Dallas on November 1, 1957, to Dean Gardner Ostrum (1922–2014) and Sarepta Mabel (née Pierpont; 1922–2021). He is the youngest of four children. Ostrum was living in Cleveland at age twelve—a city of which he was described as a native by MSNBC, and later attended North Hunterdon Regional High School in Hunterdon County, New Jersey.

Ostrum married Loretta M. Lepkowski in 1987 or 1988. They have two children, Helenka and Leif, with the latter following his father onto the stage as the leading actor in several South Lewis Central School musicals. Ostrum and his wife lived in Glenfield, New York, as recently as 2021.

Ostrum was in the sixth grade and performing at the Cleveland Play House children's theater, when he was noticed by talent agents who were searching nationwide for an actor to portray Charlie Bucket in Willy Wonka & the Chocolate Factory. The agents took Polaroid photos of Ostrum and recorded him reading from the original novel, then returned to New York. Two months later, Ostrum was called to New York for a screen test where he sang "My Country, 'Tis of Thee", and a month after that, he was contacted and given ten days to prepare to leave for filming. Ostrum left for Munich on August 10, 1970.

Peter was a child who acted—he wasn't a child actor. He had none of the obvious technique, tricks, or affectations of the kind that TV kid actors had, and continue to have. He was genuine, and his sincerity as a person shines through in his performance. He was an extremely intelligent kid, who was both self-aware and skilled at what he was doing.

In 2000, Ostrum recalled that shooting Willy Wonka in Munich was "sort of like being an exchange student for five months". Fond memories of his five months in West Germany included watching the construction of Olympiapark, for the 1972 Summer Olympics, and working with Gene Wilder and Jack Albertson. As Ostrum had not worked in film before, Wilder took it upon himself to instruct the young actor in the business. Ostrum would later describe Wilder as a quirky yet gentle gentleman who "treated people with respect and dignity". The bond that developed between the two actors was such that, even though they never saw each other again after filming Willy Wonka, Ostrum described Wilder's 2016 death as "like losing a parent"; in the 2023 documentary Remembering Gene Wilder, Ostrum remembered Wilder being fun to work with, and not speaking down to the child actors.