Susan Marie Gerbic ( GUR-bik) is an American skeptical activist living in Salinas, California.
Gerbic is the co-founder of Monterey County Skeptics, founder and leader of the Guerrilla Skepticism on Wikipedia (GSoW) project, a regular contributor to Skeptical Inquirer, The Skeptic Zone podcast, and a fellow of the Committee for Skeptical Inquiry.
Gerbic has focused much of her skeptical activism on people claiming to be clairvoyant mediums, such as Sylvia Browne, Tyler Henry, and Thomas John, whom she calls "grief vampires".