Supergirl Season 3 Finale: A Major Character Exits

(Warning: This post contains spoilers from Supergirl's Season 3 finale. Read at your own risk.)

Ahead of Monday's finale, Supergirl had some important questions to answer, like how in the world would the show explain Winn (Jeremy Jordan) becoming a recurring character next season? Monday's heart-racing episode answered that while also dropping a huge bombshell: he's not the only face you'll be seeing less of in Season 4.

The finale saw Supergirl (Melissa Benoist) defeat Reign by traveling back in time and then trapping her so that some creatures who look suspiciously like time wraiths would come and turn the World Killer to dust. But that was not before M'yrnn J'onzz (Carl Lumbly) sacrificed himself in the epic battle to save the planet, destroying our hearts in the process.

Also not so great is the news that Mon-El (Chris Wood) will not be returning for the new season. Mon-El's exit was confirmed at the end of the hour, when he decided to go with the Legion of Heroes to the future to save the world from a very distant relative of Brainiac's, who developed a virus that can wipe out all AIs.

"We've loved telling Mon-El's story, as well as the story we've told for him and Kara. We hope the fans felt that it was a satisfying conclusion," executive producer Robert Rovner told TVLine. However, you may see him again down the line. "We love working with Chris, so we'd love to have Mon-El back someday if the story takes us there and if Chris is available," he added.

Break out the tissues: Karamel is dunzo (for now).

Supergirl Super Bummer: Winn Will Play a Smaller Role Next Season

The plague prevents Brainy (Jesse Rath) from returning to the future, which also explains why he'll be sticking around full-time next season. Plus, it turns out that one of Winn's designs is the prototype for groundbreaking technology that will save many lives in the future so he, too, will be going away -- though we'll see him in a limited capacity next season.

Elsewhere, this season finale featured several other game-changing revelations: J'onn J'onzz (David Harewood) has decided to follow in his father's footsteps and will leave the DEO. Meanwhile, Alex (Chyler Leigh) will take his place as director, which is great news since she won't be in the field every day, giving her the perfect opportunity to start a family of her own.

In other exciting news, Samantha (Odette Annable) is perfectly human now. What a relief! James (Mehcad Brooks) has also revealed himself to the world as Guardian, no longer choosing to hide under his mask.

While Kara may have defeated Reign, it looks like her time-traveling strategy came with an unexpected result; there's now another Supergirl roaming around Siberia. This could spell major trouble next season. Brace yourselves, this hiatus is going to feel longer than ever.

Supergirl returns for Season 4 this fall on The CW.

(Full disclosure: TV Guide is owned by CBS, one of The CW's parent companies.)