From John Travolta to Zachary Levi, here are all the celebrities in Boston this weekend for Fan Expo

By Isaac Feldberg   BOSTON.COM  August 17, 2019 Celebrities are descending in droves this weekend for Fan Expo Boston, an annual pop-culture convention spanning Friday, Saturday and Sunday at the Boston Convention & Exhibition Center. John Travolta, of “Grease” and “Pulp Fiction” fame, will appear Sunday afternoon for a panel on the show floor’s main stage (around…