This paper aims to reexamine how traditions about the spolia opima developed with special emphasis on two crucial phases of their evolution, the time of Marcus Claudius Marcellus' dedication in 222 BC and the early years of Augustus' principate, following the restoration of the temple of Jupiter Feretrius on the Capitol. In particular, I will argue that Marcellus invented the spolia opima, that his feat shaped the entire tradition about such dedications, and that this tradition was later enhanced and "reinvented" (...) by Augustus, probably following upon renewed interest under Julius Caesar. Through an evaluation of the surviving evidence about the three canonical dedicators the possibility is explored that the spolia opima, rather than being an archaic ritual dating back to the regal period, represent a tradition invented by specific individuals at certain well-defined moments in Roman history. Augustus himself, beginning while he was still a child, was influenced by traditions about the career and achievements of M. Claudius Marcellus. Augustus' interest in Marcellus helps to explain his special focus on the spolia opima as a significant and hallowed Roman tradition. Consequently, in the late first century B.C., spolia opima were associated both with old-fashioned "republican" aspirations and also with the iconography and self-definition of the new ruling family. In this context other leading Romans of the age considered dedicating such spolia, notably M. Licinius Crassus, grandson of the triumvir, and the elder Drusus, brother of Tiberius. In addition, Virgil included the spolia opima as a recurring theme in the second half of the Aeneid. The poem reaches its climax when Aeneas kills his rival Italian leader Turnus in a duel which would have entitled him to dedicate spolia opima. (shrink)