The greatest challenger to Russian President Vladimir Putin’s rule is a man whose name the dictator won’t say and whom he has tried to kill: Alexei Navalny. Having defiantly returned to Russia after surviving a brazen assassination attempt only to be immediately detained and thrown in jail upon arrival, the opposition leader and anti-corruption crusader has rallied tens of thousands of supporters to his cause like never before — a real sign of trouble for Putin’s hold on power. Alexei Navalny has spent over a decade trying to overthrow Putin. Through slick videos, public mobilization, and even an ill-fated presidential run against the autocrat, Navalny has aimed to expose Kremlin corruption and malfeasance.