Last night's episode of "Supergirl" was full of big moments and even bigger revelations, with the biggest being the recounting of the Martian Manhunter's origin story.

"Supergirl" Recap: Politics Not Quite as Usual

In a tearful scene, J'onn J'onzz recounts the story of how the White Martians took over his planet, committing genocide on the Green Martians, including J'onn's wife and daughters. The Martian hero finishes his story, vowing to never let the White Martian kill again.

Later in the episode, J'onn battles the White Martian to a standstill, fully intending to kill her until Supergirl intervenes.

"Supergirl," starring Melissa Benoist, Calista Flockhart, David Harewood and Chyler Leigh, airs Mondays at 8 pm EST on CBS.