Sean Penn
When thousands of protesters took to Tahrir Square last September, among them was two-time Oscar winner and serial activist Sean Penn. Egyptian flag in tow, Penn walked through downtown Cairo with Egyptian actor Khaled el-Nabawi, who'd invited him as part of ongoing efforts to demonstrate that Egypt was still a safe place to visit despite the uprising. But Penn also said he was invested in the future of the cause, telling reporters that a call for freedom can't be completed overnight and predicting there would be many struggles moving forward. Penn's previous forays into activism have included touring Iraq to report on the effects of the war there, aiding rescue workers in New Orleans in the wake of Hurricane Katrina, and founding J/P Haitian Relief Organization in response to the nation's devastating 2010 earthquake.