El filibusterismo, also known by its alternative English title The Reign of Greed, is the second novel written by Philippine national hero José Rizal. It is the sequel to Noli Me Tángere and, like the first book, was written in Spanish. It was first published in 1891 in Ghent.

A filibuster, also known as a freebooter, is someone who engages in an unauthorized military expedition into a foreign country or territory to foster or support a political revolution or secession. The term is usually applied to United States citizens who incited insurrections across Latin America, particularly in the mid-19th century, usually with the goal of establishing an American-loyal regime that could later be annexed into, or serve the interests of, the United States. Probably the most notable example is the Filibuster War initiated by William Walker in Nicaragua in the 1850s.