Peter Clarence Foster (born 26 September 1962) is an Australian career criminal who has been imprisoned in Australia, United Kingdom, the United States, and Vanuatu for a variety of offences related to weight loss and other scams as well as absconding from justice. His convictions range from fraud and money laundering to contempt of court and resisting arrest.

Foster was also in the headlines for his role in helping Cherie Blair, wife of British prime minister Tony Blair, buy properties in Bristol at a discounted rate. Foster has described himself as an "international man of mischief".

Foster began marketing and selling products at 19 years of age. Nicknamed "kid tycoon" and the "milkshake tycoon", Foster was promoting themed nights at a Gold Coast discothèque two years before he was legally allowed in the club and became a boxing promoter at 17.

At 20, Foster was fined by an Australian court for attempting to make a fraudulent insurance claim when a boxing match he was promoting fell through.

The following year, Foster became a television producer and filmed a documentary with Muhammad Ali while living several weeks with him in his home in Los Angeles. He was declared bankrupt after promoting an Ali bout in Australia that did not eventuate and marketing a method for quitting smoking.

Foster was also known for his relationship with model Samantha Fox, whom he hired to promote his weight loss tea. She later distanced herself from him and remarked:

I'm old enough now to know that I'd never be taken in again by the likes of Peter Foster. But then, I was 22 and impressionable. My parents had split and here was a man who was clever, manipulative and domineering. I came close to marrying him because I was so vulnerable.

— Samantha Fox, quoted in "Serial fraudster who keeps bouncing back", The Guardian, 6 December 2002