'Supergirl': SPOILER Dies in "O Brother, Where Art Thou?"

On Supergirl this season, the tensions in both National City and the country have been building. [...]

On Supergirl this season, the tensions in both National City and the country have been building. The Children of Liberty, led by Ben Lockwood, have stirred up the anti-alien sentiment to a fever pitch, prompting violent attacks against the non-human citizens. On the other side of things, The Elite has taken an extreme approach to countering the Children of Liberty with the innocent citizens -- alien and otherwise -- caught between them. Tonight, those tensions took a deadly turn with the death of a significant character.

Spoilers for tonight's episode of Supergirl, "O Brother, Where Art Thou?" below.

Last week in the closing moments of Supergirl, James Olsen was shot in the back as he left his office at CatCo. His condition was left a mystery until tonight when the episode revealed that he was in dire condition and near death even with medical intervention. However, despite his grave injuries, James will live to see another day. Instead, it's Manchester Black who breathed his last.

When J'onn finds out that James has been shot and is in serious condition, the Martian immediately believes that Manchester is behind the attack. After all, Manchester has not just been trying to provoke J'onn to violence but actually threatened to bring harm to those J'onn cares about in order to do it. James' injuries prompt J'onn to go after Manchester and while the leader of The Elite manages to evade him for a bit things eventually come to a head in a confrontation at the National City dam.

J'onn is in quite a state when he confronts Manchester. Manchester has been in his head, manipulating his visions, exploiting his religious practices, and even has stolen the Staff of Kalar that was previously the possession of his father, the late M'yrnn. By the time Manchester and J'onn collide, J'onn has decided to do whatever it takes to protect those he loves as well as stop Manchester from creating an increasingly dangerous situation for the world.

Using the Staff, J'onn kills Manchester Black, but that doesn't mean J'onn's conflict is over. As Manchester dies, he calls J'onn "beautiful" and as the episode ends it's clear that J'onn is deeply shaken by his actions. Despite retrieving Brainy's stolen Legion ring, J'onn is unable to return it to him. Instead, he leaves that to Kara as he no longer feels like he is a man of peace -- a huge failure in J'onn's eyes. It's something that will drive J'onn's story forward in upcoming episodes, according to executive producer Robert Rovner.

"I think as it kind of puts him in an identity crisis at the end of this episode that he will deal with in episode 17 in particular," Rovner said.

Are you sad to see Manchester Black go? Let us know in the comments below.

Supergirl airs Sundays at 8 p.m. ET on The CW.