ABC's Once Upon a Time boldly killed off a fan favorite character in Sunday night's winter finale, and many fans are upset about it.

Does Hook Still Love Emma 'Deep Down' On 'Once Upon a Time'?

Last night's epic midseason finale of Once Upon a Time left many fans in shambles. Emma (Jennifer Morrison) tried to sacrifice herself for the good of Storybrooke by channeling the darkness into Excalibur, but Hook (Colin O'Donoghue) stole the sword.

However, as things went along, Hook had a change of heart when Nimue (Caroline Ford) started choking Emma, causing him to lash out against the Dark Ones. He decided the best move was to sacrifice himself in order to save both Emma and the citizens of Storybrooke. Emma stabbed Hook, killing him and sending him to the underworld.

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But there is still hope. In the second half of the season, Emma will try to retrieve Hook from the underworld and revive him by splitting her own heart.

Though all is not lost, many Once Upon a Time fans are heartbroken and upset over this turn of events. Check out the most emotional tweets below.

Once Upon a Time will return for the second half of season 5 on Sunday, March 6 at 8 p.m. ET/PT on ABC.