Warning! The following contains spoilers for The Flash episode "Lose Yourself." Read at your own risk!
The Thinker put Team Flash on the ropes and took over Ralph Dibny at the end of the episode, but it wasn't the Elongated Man The Flash fans were crying for. After a brief battle with DeVoe, Killer Frost quickly found herself outmatched, and before anyone knew what happened, Caitlin Snow was getting thrown up against a wall and The Thinker was pulling the frost powers out of her body. Afterwards, Caitlin urged Cisco and Harry to run some tests which confirmed she had no dark matter in her body, and meant that her Killer Frost persona was no longer around. Yes, The Flash killed Killer Frost, and Twitter was pissed:
Pissed might even be an understatement, because while The Flash Twitter feed featured a few mentions of the team's loss of Ralph Dibny, it was mainly about fans wanting to express their distaste for Killer Frost's quick exit. There were no tearful goodbyes, no noble sacrificial acts that made her heroic, or even a drawn-out battle that made it look like a challenge. In all honesty, it might've been the most disrespectful death the Arrow-verse has delivered since its unceremonious offing of Amanda Waller:
The Flash fans weren't just mad about the level of disrespect shown to Killer Frost's exit, however, but also how little her story and journey with her split personality seemed to matter in Season 4. Caitlin and Killer Frost had a strong start when the characters were intertwined with Katee Sackhoff's Amunet Black, but once The Thinker storyline got fully underway, the storyline slowly died in order to show more of Ralph developing as a hero and Team Flash's attempts to save the bus metas. The creative decision by the show's writers was not well received by some fans, who seemed to resent Ralph for the spotlight he took off of Caitlin:
Fans have a right to react how they want, but perhaps it's premature to flame The Flash writing staff over the web when it's not a sure thing Killer Frost is dead. This show is set in a universe where people seem to come back one way or another all the time, and with Caitlin Snow still alive and well it's very possible Killer Frost is still in there somewhere. After all, DeVoe didn't take over Caitlin's body, nor did he start using frost powers immediately after sapping Caitlin's powers from her, so how do we know Killer Frost is really gone for good?
That said, if Killer Frost is coming back, it doesn't appear to happen in the next episode. Next week's promo teased the return of Leonard Snart who will be helping Team Flash keep that nuclear meta from a few episodes back cool while he gets shipped to a more secure facility. Snart's presence and the cold gun would be a redundancy if Caitlin still had her powers, so we can speculate that Killer Frost will be gone for at least a week if she is returning. In the meantime, the fanbase will continue to tweet about how bad a decision The Flash staff made if this death is indeed permanent.