Release: 2015
Pretty much a stand-alone, Ant-Man was designed to be a palate-cleanser after Age Of Ultron, but its post-credits scene tied to to Civil War as a prologue, so there's no getting around its position. We also saw the first mention of the Quantum Realm, importantly. This is also a good time to watch most of the Netflix MCU shows, incidentally, if you can face it.