'Krypton': What Is the Green Death?

Tonight's Krypton continued exploring the DC mythos in new ways -- while introducing a familiar concept in the process.

Spoilers for tonight's episode of Krypton, "House of El", below!

The episode saw Seg (Cameron Cuffe) coming more to terms with his family's legacy with the help of a Phantom Zone hologram projection of his grandfather, Val-El (Ian McElhinney).

At one point, Val began explaining pieces of Krypton's history -- including the mention of the "Green Death", something that one of the previous El family members had found a cure for.

So, what exactly is the Green Death? Interestingly, it originated in a 1944 episode of the Adventures of Superman serial, which was appropriately titled "The Green Death". The episode ended up being one of the first introductions of Kryptonite, which ultimately carried over to the comics.

In the previous Superman lore, the Green Death has a much more specific connection to another ancestor of Superman's: his father, Jor-El.

When Jor-El became an adult, he realized that a large number of Kryptonians were being killed by a "Green Plague". Jor-El began researching the plague, and found that it was growing radiation produced by Krypton's core, something that would ultimately lead to the planet's explosion.

So, the "Green Death" ultimately ended up being one of the first introductions of Kryptonite. And admittedly, the introduction of the "Green Death" into Krypton raises a few questions; namely in the fact that a completely different family member dealt with it, decades before Seg.

But in a way, fans can understand why the show would essentially want the "Green Death" to be an event that already happened, so Seg and company can focus on more pressing threats. And ultimately, it shows how Krypton is combining DC Comics lore with its own flair, something the show has been setting out to do.

"We haven't really seen much of this world before and it's just this open book and allows us to tell a story that hasn't been told," Welsh told reporters during a recent set visit. "There's still plenty more Superman stories to tell, but there's already been a ton of those and there will continue to be. Here's a fresh opportunity to tell this -- to explore a part of the DC universe which is super important, and it's relatively unexplored. It's less about not having Superman but more about it being a prequel is something that we've discussed as being a challenge that we face."

Krypton airs Wednesdays at 10/9c on Syfy.