French naturalists at the Muséum Nationale d'Histoire Naturelle in Paris in the early nineteenth century recognized that their individual and collective successes were intimately linked to questions of power over specimens. France's strength abroad affected the growth of the museum's collections. At the museum, preserving, naming, classifying, displaying, interpreting, and otherwise deploying specimens went hand in hand with promoting scientific theories, advancing scientific careers, and instructing the public. The control of specimens, both literally and figuratively, was the museum's ongoing concern. The leopard in this essay's title, a live specimen confiscated from the streets of Paris in 1793, serves here to represent the tensions created in an existing order of things by the introduction of a potentially disruptive agent. The essay explores the life of the museum and the interrelations among its naturalists, the special challenges created by the establishment of a menagerie, and the histories of particular specimens and ideas.