Rebeccah Mercer is an American conservative donor and heiress to the fortune built by her father, Robert Mercer, co-CEO of the hedge fund Renaissance Technologies. She has funded numerous right-wing organizations, including Breitbart News and the Government Accountability Institute (GAI), contributing to their operations and investigative projects critical of political opponents like Hillary Clinton. Her philanthropy aligns with the Mercer family's broader support for conservative causes, often channeled through the Mercer Family Foundation. Less publicly prominent than her sister Rebekah Mercer, who oversees the family foundation, Rebeccah has focused on media and research initiatives. She has documented ties to conservative networks, including allegations of straw donor arrangements such as to Yoram Hazony. The family's financial influence has shaped outlets like Breitbart and think tanks like GAI, which produced research used in 2016 election efforts.