Just googled. Marcos is the leader of the Zapatista Army of National Liberation in Mexico.
I'm surprised you haven't heard of him. The U.S. media loves that guy. Basically, he controls some rebel group in Chiapas. Every few years, he takes over a town, then when the Federales are sent in, he hides back in the hills. Then our media goes in and gives him long, loving interviews for "60 Minutes" and other news shows so he can give his Indian rights/Socialism/Secession spiel. Then everyone forgets about him until the next time he pops up.