The Marvel universe is so packed with detail that some concepts are just as important to understand as people or places. One such scientifc concept present in the MCU are the iconic Pym Particles, which are key to the narratives of Ant-Man and Avengers: Endgame. Pym Particles first appeared on-screen in 2015's Ant-Man, which depicted their initial discovery by scientist Hank Pym. That film provided a great showcase for the particle's capabilities, and their drawbacks as they became the primary item of interest in multiple films.