This article reassesses John Sutter's role in borderlands history as a destabilizing influence in Mexican California and model for filibusters of the 1850s. Nominally a Mexican citizen, his national loyalties were slippery. In effect, Sutter was an independent filibuster before 1846; californios and the Mexican government regarded him as such. After 1848 his contributions to the American settlement and conquest of California (suitably sanitized and mythologized) made him a pioneer hero who had shown filibusters what might be done in Latin America with a small army and a lot of swagger. Sutter approved and supported Central American filibusters in the 1850s; at least one of his sons fought with filibusters. One of the most colorful characters in the history of the American West, Sutter had eccentricities and personal failings that make him easy to parody. This article shows him in a more serious light. His actions in California had lasting importance there and repercussions elsewhere in Latin America.