Claire Regina Fox is a British libertarian writer and politician. She is the director and founder of the think tank the Institute of Ideas, a trading name of the Academy of Ideas.

A lifelong Eurosceptic, she was previously a member of the Trotskyist British Revolutionary Communist Party but later began identifying as a libertarian. She became a registered supporter of the Brexit Party shortly after its formation and was elected as an MEP in the 2019 European Parliament election. She was nominated for a peerage by the Boris Johnson-led Conservative government in 2020, despite her past opposition to the existence of the House of Lords.