Frank J. Gaffney Jr. (born April 5, 1953, in Pittsburgh, Pennsylvania) is an American conservative and neoconservative foreign policy and national security analyst, counterterrorism expert, writer, and former Reagan administration official. Born to a family with deep roots in law and public service, including Catholic heritage and Irish ancestry—his father a lawyer and grandfather a city solicitor who faced anti-Catholic discrimination—Gaffney began his career in the 1970s as a legislative aide to Democratic Senator Henry M. Jackson, working closely with neoconservative Richard Perle. In 1987, he served as acting Assistant Secretary of Defense for International Security Policy under President Ronald Reagan, overseeing nuclear forces, arms control, and missile defense policies, for which he received the Department of Defense Medal for Distinguished Public Service. He was an outspoken opponent of the Comprehensive Test Ban Treaty in the 1990s, circulating materials alleging Russian duplicity, and later received the Zionist Organization of America's Louis Brandeis Award in 2003.

He is the founder, former president, executive director, and executive chairman of the Center for Security Policy (CSP), a Washington, D.C.-based conservative, hawkish, and neoconservative think tank focused on national security, defense, counterterrorism, and anti-Islamist advocacy, which he established in 1988 and has transformed into an influential force shaping conservative discourse. Gaffney is a prominent counter-jihad figure known for his leadership of CSP and his influential role in conservative and counter-jihad policy circles. He has authored numerous articles and books for outlets such as The Washington Times, Townhall, and Big Peace, and hosts the radio program Secure Freedom Radio, along with TV programs. His hawkish foreign policy views focus on threats from radical Islam, Islamist extremism, nuclear proliferation, and adversarial nations including Iran, China, and Russia. He promotes controversial claims such as a 'stealth jihad' to impose Sharia law in the U.S., the need to ban Sharia to protect constitutional freedoms, and alleges Muslim Brotherhood infiltration of the U.S. government. CSP is noted for aggressive counterterrorism measures and anti-Muslim advocacy, drawing criticism from groups like the Southern Poverty Law Center, which has labeled him an Islamophobe and his think tank a hate group since 2016 for fostering Islamophobia, contributing to an 'Islamophobia network,' and promoting conspiracy theories, including claims of Muslim Brotherhood ties to U.S. officials and unfounded allegations about Barack Obama's faith and birthplace (birtherism).

Gaffney has influenced conservative politics through briefings to organizations like the American Freedom Law Center and ACT for America, advisory roles on counterterrorism and Iran policy, media contributions including Fox News, associations with the Hudson Institute, and collaborations with figures like Walid Shoebat. He received support from donors including Donors Capital Fund and endorsed conspiracy theories such as birtherism against President Obama. His influence extended to the Trump administration, where his ideas reportedly impacted national security appointees like Michael Flynn and Mike Pompeo, and CSP influenced policies including the Muslim travel ban, though he faced backlash for his extreme views, including a ban from CPAC events in 2011. Despite widespread allegations of fear-mongering, spreading anti-Muslim conspiracy theories, and fostering division—with no major legal troubles documented—Gaffney remains a prominent conservative voice, actively commenting on platforms like X (formerly Twitter) under the handle @frankgaffney. His career spans from Democratic hawkishness during the Jackson era to modern Republican neoconservatism, establishing him as a persistent and influential figure in security affairs and counterterrorism policy aimed at countering Islamist influences in the U.S. government and military, while highlighting existential threats from adversarial forces.