The Flash: 10 best episodes, ranked

10. “What’s Past Is Prologue” (Season 5, Episode 8)

We all love a good 100th episode, so The Flash had to deliver on that front (even if its fifth season wasn’t its best). Thankfully, the Arrowverse series felt the same way and pulled out all the stops to produce an episode that not only celebrates everything that led up to that moment but also elevated the rest of the season.

Successfully using what’s going on in the present to provide an opportunity to revisit the past, “What’s Past Is Prologue” expertly plays with the timeline to offer up some wonderful nostalgia that Flash fans certainly appreciated.

With Cicada proving to be an unstoppable threat due to his power-dampening dagger, Team Flash comes up with a plan to finally depower him – a plan that involves tracking down various items and knowledge that only parts of their past can provide. And as a result, Barry and his daughter Nora head into the timeline and cross paths with the Reverse-Flash, Zoom, Savitar and even a Time Wraith.

Team Flash’s plan doesn’t work in the end, but it was all worth it just to revisit the past and celebrate The Flash. It was also worth it just to see Killer Frost return and stand up to Cicada in a way that nobody else could!