Stavros Niarchos III is the eldest son of Philippe Niarchos and his third wife Victoria (born Guinness).
He is named for his grandfather, shipping tycoon Stavros Niarchos.
Stavros Niarchos was a student in the Collège Stanislas in Paris. His senior year of high school was spent at Seabury Hall, a college preparatory school located in Makawao on Maui, Hawaii.
After high school, Niarchos attended the University of Southern California Film School where he graduated and received his diploma in May of 2007.
A tall, athletic, blond, Niarchos is best-known for dating Paris Hilton, Mary-Kate Olsen, and Lindsay Lohan. He also appeared with actress Kate Bosworth in her January 2005 GQ magazine spread.
Niarchos is of Greek, Irish, Austrian and Mexican ancestry. Niarchos was born in New York City and grew up in Paris, France.