Barre Seid is an American billionaire businessman, manufacturing executive, reclusive philanthropist, and major conservative megadonor. Born in 1932 in Chicago to Russian Jewish immigrant parents, he grew up in a working-class environment on Chicago's industrial South Side. He attended the University of Chicago before serving two years in the U.S. Army. Upon returning to Chicago, he joined Trippe Manufacturing as an assistant to owner Graham Trippe and rose to become president in the mid-1960s. Under his leadership, the company, later renamed Tripp Lite, became a prominent manufacturer of electrical power protection and connectivity products, including surge protectors and uninterruptible power supplies, achieving annual revenues exceeding $200 million by the 2010s. Seid acquired full ownership of Tripp Lite over time, maintaining control for decades as its owner and building it into a significant enterprise.

In 2021, prior to its sale to Eaton Corporation for $1.65 billion, he transferred approximately 88% of his shares—valued at around $1.6 billion—to the Marble Freedom Trust, a 501(c)(4) nonprofit and dark money group aligned with conservative causes and led by Federalist Society co-chairman and conservative judicial activist Leonard Leo. This marked one of the largest single contributions to a politically focused nonprofit in U.S. history. Seid has been a prolific donor of hundreds of millions of dollars to right-wing organizations through his family foundation and other channels, including anonymous donations routed through donor-advised funds like the Donors Capital Fund and DonorsTrust, as well as the Clarion Fund (which operates the Clarion Project, known for anti-Islam advocacy), Americans for Prosperity (via straw donors), various think tanks like the Heritage Foundation, and judicial activism efforts. His philanthropy has supported efforts criticized for promoting Islamophobia and attacking climate science, positioning him as a key figure in conservative influence networks, particularly in areas like judicial appointments and cultural issues.

Extremely private and reclusive, Seid avoids public appearances, has no known social media presence, and maintains a low-profile approach to philanthropy, often enabling anonymous funding of partisan causes, which has drawn scrutiny despite limited personal details available about him. His financial influence underscores his role as a billionaire industrialist and donor in shaping ideological battles.