An anniversary recount sticker showing numbers from 1985 and 2015. Source.
The Guerrilla Girls are a group of female activists which formed in 1985. They wear masks in public so people focus on the issues they are fighting for and not about who they are. They use humor and outrageous visuals to expose gender bias. They are devoted to what they do: fighting gender and racial inequality. To keep their anonymity they named themselves after deceased female artists.