John Horgan (psychologist)
John G. Horgan (born 1974) is a Distinguished University Professor of Psychology at Georgia State University in Atlanta. He studies how people become involved in terrorism and how they disengage or deradicalize. The European Eye on Radicalization has described him as the world’s leading expert on the psychology of terrorism. Since 2019, he has led a Department of Homeland Security–funded project researching the incel subculture.
Horgan grew up in Castleisland, County Kerry, Ireland. He earned a PhD in applied psychology from University College Cork in 2000 and began researching Irish Republican movements, including fundraising by the Provisional IRA.
He has held senior roles at several universities. At UMass Lowell he directed the Center for Terrorism & Security Studies; at Penn State he led the International Center for the Study of Terrorism. He has received multiple research grants, including the Airey Neave Trust Fellowship in 2006. After consulting for the FBI’s Behavioral Analysis Unit in 2010, he joined the FBI’s NCAVC advisory groups until the NCAVC was dissolved in 2012.
His research has appeared in journals such as Terrorism and Political Violence and Studies in Conflict & Terrorism. He has written books including The Psychology of Terrorism, Divided We Stand, and The Future of Terrorism (with Max Taylor). He is the editor of Terrorism and Political Violence and serves on several editorial boards. He also leads Georgia State’s Violent Extremism Research Group.
This page was last edited on 3 February 2026, at 16:00 (CET).