Katharine Ann Johnson "Kathy" Rayner (born 1944/1945) is an American billionaire heiress.
She was born Katharine Ann Johnson to Anne Cox Chambers and Louis G. Johnson. Her maternal grandfather is James M. Cox. She has a sister Margaretta Taylor, and a half-brother James Cox Chambers, from her mother's second marriage.
In 2015, Rayner's mother Anne Cox Chambers distributed her 49% share in Cox Enterprises equally between her three children. As of February 2026, her net worth is US$6.8 billion.
In 2019, she donated over $5 million to the Animal Medical Center in New York City.
She has been married twice. She married Jesse Kornbluth, a magazine writer, on May 26, 1984. They eventually divorced. Her second husband was painter and travel writer William P. "Billy" Rayner, who died on January 22, 2018, at the age of 88.
Rayner lives in East Hampton, New York.