Zak Bagans claims that he was possessed on two different episodes of Ghost Adventures. The first time was during season 2, episode 9 Preston Castle, which was filmed in Ione, California. It first aired June 5, 2009.
The second alleged possession of Bagans was during season 3, episode 19 Poveglia Island, which was filmed in Italy. It first aired on November 13, 2009.
Nick Goff, co-investigator and executive producer of Ghost Adventures says he was possessed during season 2, episode 15 Moon River Brewing Company, filmed in Savannah, Georgia. It first aired on July 17, 2009.
Aaron Goodwin, co-investigator of Ghost Adventures claims to have been under the influence of a dark spirit, but not necessarily possessed during season 4, episode 29 Return to Bobby Mackey's Music World, filmed in Wilder, Kentucky (original air date October 1, 2010). A second occurrence he says took place during season 5, episode 57 Winchester Mystery House, filmed in San Jose, California (original air date October 14, 2011).
Of interest, Season 7 of Ghost Adventures will continue on January 11, 2013 with brand new episodes. Upcoming investigations will take place at Sailor's Snug Harbor in Staten Island, New York; Wyoming Frontier Prison in Rawlins, Wyoming; and the Mystere Mansion in New Orleans, Louisiana.