后三头同盟是历史学家给予屋大维(Augustus)、马克·安东尼(Marcus Antonius)和雷必达(Marcus Aemilius Lepidus)组成的官方政治同盟的名称，但大多数的历史学家还是将这三人组盟的名称是“后三雄”，与凯撒、克拉苏和庞培所组的“前三雄”以兹分别。这同盟成立于公元前43年11月27日，维持至公元前33年。不同于较出名的前三头同盟，后三头同盟是官方组织（如果宪法还没规定），在罗马帝国获法律认可取得压倒性优势，他们的统治大权高于其他地方官员，包括执政官。

The Second Triumvirate is the name historians have given to the official political alliance of Gaius Octavius (Octavian, Caesar Augustus), Marcus Antonius (Mark Antony), and Marcus Aemilius Lepidus, formed on 27 November 43 BC with the enactment of the Lex Titia, the adoption of which is viewed as marking the end of the Roman Republic. The Triumvirate existed for two five-year terms, covering the period 43 BC to 33 BC. Unlike the earlier First Triumvirate, the Second Triumvirate was an official, legally established institution, whose overwhelming power in the Roman state was given full legal sanction and whose imperium maius outranked that of all other magistrates, including the consuls.