'Once Upon a Time' Winter Finale Sneak Peek

The winter finale of OUAT airs Sunday at 8 p.m. ET/PT.

The Dark Ones prepare to obliterate light magic once and for all in this week's episode of Once Upon a Time ("Swan Song"), airing Sunday, December 6 at 8 p.m. ET/PT.

The dark siege of Storybrooke is underway as all of the resurrected Dark Ones target a living soul for sacrifice so that they can return to the realm of the living. With doom imminent, Gold advises Mary Margaret, David and the rest of the heroes to spend their last fleeting moments enjoying the company of their loved ones. Emma, however, refuses to give up, knowing that she is responsible for righting all the poor choices she made as Dark One - there's only one problem, Dark Hook. When they face-off with the fate of Storybrooke at stake, Hook's actions will devastate Emma in a way no one saw coming. In a Fairy Tale Land flashback, the Evil Queen tests Hook's mettle by forcing him to confront a demon from his past before contracting him to dispatch one from hers.

Watch a sneak peek below:

'Once Upon a Time' Sneak Peek: Broken Heart

Sean Maguire, Lana Parrilla and Rebecca Mader. Photo Credit:
ABC/Eike Schroter

The fate of Storybrooke hangs in the balance when Emma and Hook's relationship is tested as never before in this week's episode of Once Upon a Time ("Broken Heart"), airing Sunday, November 29, starting at 8 p.m. ET/PT.

In a Camelot flashback, Hook becomes a Dark One and his lust for revenge against Rumplestiltskin is reignited. When Emma and Hook disagree about their best course of action, the final pieces of the puzzle are revealed as events in Camelot catch up to the present and we witness a charged confrontation between the forces of light and dark that sends our heroes on a collision course with destiny. Meanwhile, in Storybrooke, Hook's centuries old lust for revenge against Gold puts both of their fates in jeopardy while Emma's love faces the ultimate test as she tries to convince Hook to turn away from the darkness before she, Mary Margaret, David and Regina embark on a new mission as an unsuspected evil is released.

Watch a sneak peek below:

'Once Upon a Time' Sneak Peek: Merida Meets Mulan

"You may not need a man to teach you how to fight, but you can
learn a thing or two from me," Mulan tells Merida.

The heroes' Camelot quest culminates with an impossible decision Emma must make in a special two-hour Once Upon a Time event, airing Sunday, November 15, starting at 8 p.m. ET/PT.

The back-to back episodes begin with "Birth," as tensions in Camelot come to a head when Merlin, now under Arthur's control, delivers an ultimatum to Emma: hand over the Dark One dagger and the Promethean spark or he will kill her entire family. Refusing to give in, Emma and our heroes face off against Arthur, Merlin and Zelena in an epic battle of magic and will. Just when the end is in sight, Emma is forced to make a gut-wrenching choice that no one saw coming. Back in Storybrooke, Zelena's pregnancy mysteriously accelerates and Hook goes to new and desperate lengths to get answers from the Dark Swan.

In the second hour, "The Bear King," Zelena and Arthur journey to DunBroch on a mission to retrieve an enchanted relic that will provide the advantage they need to vanquish Emma and our heroes. Their path will cross with Merida's, who is on a journey of her own to pay a debt that her father, King Fergus, owed to the Witch when he died. Merida enlists the help of two friends, Mulan and Ruby, but, in order to satisfy the Witch and save DunBroch, she first must discover the identity of the knight who killed her father. In flashbacks, Merida learns about bravery and honor as she trains for combat and rides alongside Fergus into the infamous battle that claims his life.

Watch a sneak peek below:

'Once Upon a Time' Preview: Can Emma Be Saved?

Hook wants specifics about the plan to save Emma.

Emma and Merlin embark on a perilous quest to retrieve Prometheus' fire from the birthplace of dark magic on this week's new episode of Once Upon a Time ("Nimue"), airing Sunday, November 8 at 8 p.m. ET/PT.

In Camelot, Merlin spearheads a mission to reunite the dagger with Excalibur so he can use the weapon to save Emma from the darkness threatening her soul. With Zelena in tow, Hook, Mary Margaret, David, Regina and Robin steal into Arthur's castle to take the broken sword from the maniacal king. Meanwhile, Merlin brings Emma along on a journey to confront his ancient nemesis and retrieve the sacred spark he'll need to reforge Excalibur. Both parties are tested, but one suffers a blow that could derail the entire operation.

In a flashback to long before the Age of Arthur, young Merlin finds purpose after he is blessed with magic and immortality, but when he falls in love with a young refugee named Nimue, everything changes for Merlin, as their romance starts a chain of events that touches every one of our present day heroes.

In the sneak peek below, Hook, Mary Margaret, David, Regina and Robin gather to find out how to save Emma from the darkness threatening her soul.

'Once Upon a Time' Preview: Merida Breaks Out of Jail

Paul Telfer (left) as Lord Macintosh on Once Upon a Time.

Days of our Lives alum Paul Telfer (ex-Xander Cook) guest stars as Lord Macintosh on this week's episode of Once Upon a Time ("The Bear and the Bow"), airing Sunday, November 1 at 8 p.m. ET/PT on ABC.

In a Camelot flashback, a chance encounter with Merlin, David, Hook and Belle gives Merida new hope in her quest to save her brothers from the usurping clans of DunBroch. Unwilling to leave anything up to fate, Merida brings Belle along on a dangerous journey that culminates with an invaluable lesson in bravery.

In Storybrooke, Regina, Mary Margaret and David discover the spell that would allow one of Merlin's chosen to communicate with him, but when Arthur fails to reach the missing sorcerer the heroes grow suspicious. Meanwhile, Emma commands Merida to kill Belle in hopes of forcing Mr. Gold's heroic transformation. With Merida unable to disobey Emma's orders, Gold must find the courage to fight for Belle's life or risk losing her forever.

In the sneak peek below, Merlin (Elliott Knight), David (Josh Dallas), Hook (Colin O'Donoghue) and Belle (Emilie de Ravin) sneak into the dungeon at Arthur's castle to free Merida (Amy Manson) and Lancelot (Sinqua Walls).

'Once Upon a Time' Preview: Henry Turns to Dark Swan for Help

Jared Gilmore plays Henry on Once Upon a Time.

Once Upon a Time Season 5 continues with a new episode ("Dreamcatcher") on Sunday, October 25 at 8 p.m. ET/PT on ABC.

In Camelot, as Mary Margaret and David attempt to retrieve the Dark One dagger, Emma uses a dreamcatcher to look into the past to see how Merlin was transformed into a tree. Together, Emma and Regina figure out the critical ingredient they must acquire to free Merlin, but it's a race against Arthur, who does not want Merlin released. Meanwhile, with encouragement from his moms, Henry musters up the courage to ask Violet on a date. Back in Storybrooke, the heroes break into Emma's house hoping to locate Gold, but what they find will give them a glimpse of Emma's end game. Far from prying eyes, Merida sets about the mission Emma has tasked her with and begins molding Gold into the hero they need to draw Excalibur.

In the sneak peek below, when Henry sees his crush Violet's sadness over her missing horse, he turns to the one person he knows can help: Emma.

'Once Upon a Time' Preview: Regina Makes a Promise to Zelena

Regina (Lana Parrilla) allows a muted Zelena (Rebecca Mader) to speak.

Once Upon a Time Season 5 continues with a new episode ("Siege Perilous") on Sunday, October 11 at 8 p.m. ET/PT on ABC.

In Camelot, the heroes feverishly work to free Merlin. Determined to help Emma, David embarks on a quest to retrieve a magical relic that Regina could use to communicate with the imprisoned sorcerer, but, when David leaves, Arthur insists on joining him because the dangers ahead are greater than he can imagine. Meanwhile, Mary Margaret discovers the fate of her old friend Lancelot. Back in Storybrooke, Arthur seeks David's help to catch a thief who threatens the safety of the citizens of Camelot. Across town, Emma reaches out to a conflicted Hook as she sets about her plan to draw Excalibur from the stone

In the sneak peek below, Regina (Lana Parrilla) allows a muted Zelena (Rebecca Mader) to speak and confronts her sister about taking away Robin's (Sean Maguire) baby.

ONCE UPON A TIME Season Finale Preview: "And Straight On 'Til Morning"

Photo: ABC

The inhabitants of Storybrooke brace themselves for the end when Greg and Tamara detonate the trigger Regina had placed within the curse, with the annihilation of the town and its residents imminent; and Mr. Gold mourns the loss of his son, Bae/Neal. Meanwhile, back in Neverland of the past, Hook discovers his connection to a young Bae after he rescues him from the sea and soon realizes that the Lost Boys are in hot pursuit of the boy, on the season finale of ONCE UPON A TIME, Sunday May 12 at 8 p.m. ET/PT on ABC.

Watch a sneak peek below:

ONCE UPON A TIME Preview: "Second Star to the Right"

Photo: ABC

The sophomore season of ONCE UPON A TIME continues on Sunday, May 5 at 8 p.m. ET/PT on ABC.

In "Second Star to the Right," Emma, Mary Margaret and David go in search of Regina when they discover that she - along with some magic beans - have gone missing. But against Neal's protests, Emma still believes that Tamara had something to do with Regina's disappearance; and Mr. Gold contemplates telling Lacey the truth about his ability to conjure magic.

ONCE UPON A TIME Preview: "The Evil Queen"

Photo: ABC

The sophomore season of ONCE UPON A TIME continues on Sunday, April 28 at 8 p.m. ET/PT on ABC.

In "The Evil Queen," with the aid of Hook, Regina attempts to put a plan in motion that will help transport herself and Henry back to Fairytale land. But her plan revolves around a fail-safe that was planted within the curse, which if triggered could wipe Storybrooke off the map - and kill all of its inhabitants; and Emma's suspicions about Tamara grow. Meanwhile, in the fairytale land that was, the Evil Queen asks Rumplestiltskin to transform her into an unrecognizable peasant in order to kill an unsuspecting Snow White, with the twisted aim of earning the love and respect of her subjects.

Watch a few sneak peek videos below:

ONCE UPON A TIME Preview: "Lacey" With Guest Star Jorge Garcia

Photo: ABC

The sophomore season of ONCE UPON A TIME continues on Sunday, April 21 at 8 p.m. ET/PT on ABC.

In "Lacey," Mr. Gold enlists the aid of David to help him try to jog Belle's now cursed memories and get her to love him again; and when it is revealed that the magic beans Anton (Jorge Garcia, LOST) and the dwarves have been harvesting have begun to grow and could possibly transport everybody home, Emma is torn over whether she would want to live in fairytale land or stay in our world.

PREVIEW: ONCE UPON A TIME ("Selfless, Brave and True")

Photo: ABC

The sophomore season of ONCE UPON A TIME continues on Sunday, March 24 at 8 p.m. ET/PT on ABC.

In "Selfless, Brave and True," while Mary Margaret goes off on her own in an attempt to come to grips with what she did to Cora and how her deed has affected her, she stumbles upon August, who has hidden himself away from the others and is completely made of wood -- ashamed at the actions he has taken in life; and Emma is shocked when Neal invites his fiancée, Tamara, to come to Storybrooke.

PREVIEW: ONCE UPON A TIME ("Welcome to Storybrooke")

Photo: ABC

The sophomore season of ONCE UPON A TIME continues on Sunday, March 17 at 8 p.m. ET/PT on ABC.

In "Welcome to Storybrooke," Emma, David and Mr. Gold must protect Mary Margaret against Regina, who is out for revenge and has made it her mission to kill Mary; and Henry, fed up with all of the feuding, devises a plan to put an end to magic. Meanwhile, Regina discovers that a father and son have somehow found their way into her allegedly undetectable town as she and the fairytale characters deal with the effects of the newly cast curse 28 years prior.

Watch a few sneak peek videos below:

PREVIEW: ONCE UPON A TIME ("The Miller's Daughter")

Photo: ABC

The sophomore season of ONCE UPON A TIME continues on Sunday, March 10 at 8 p.m. ET/PT on ABC.

In "The Miller's Daughter," Cora's desire to rid herself of Rumplestiltskin in order to take his place as The Dark One takes one step closer to becoming reality as she and Regina try to overpower a dying Mr. Gold, and Mary Margaret is once again tempted by dark magic.

Meanwhile, in the fairytale land that was, Rumplestiltskin agrees to offer his services to a younger Cora - for a price - when the king calls her bluff and orders her to actually follow through on her boast of being able to spin straw into gold.

Watch a sneak peek below:

PREVIEW: "The Queen is Dead" On ONCE UPON A TIME

Photo: ABC

The sophomore season of ONCE UPON A TIME continues on Sunday, March 3 at 8 p.m. ET/PT on ABC.

In "The Queen is Dead," upon discovering Cora and Regina's plan to find and take possession of Rumplestiltskin's dagger, Mary Margaret, with the aid of David and Mother Superior, makes it her mission to find it first; and while Mr. Gold continues his quest in New York to reunite with son Bae, Hook devises a plan to rid himself of a crocodile.

Meanwhile, in the fairytale land that was, the Blue Fairy offers Snow White an unconventional enchantment that could help save her dying mother, Queen Eva.

Watch a sneak peek below:

PREVIEW: ONCE UPON A TIME Winter Finale ("Queen of Hearts")

Photo: ABC

Season 2 of ONCE UPON A TIME continues on Sunday, December 2 at 8 p.m. ET/PT on ABC.

In the winter finale, "Queen of Hearts," Cora and Hook face off with Mary Margaret and Emma in a race to secure the compass, which will point its holder to the portal into Storybrooke. But back on the other side, Regina and Mr. Gold, desperate to keep Cora out, put a plan into action that would kill anyone entering the portal - placing Mary Margaret's and Emma's lives in danger as well.

PREVIEW: ONCE UPON A TIME ("Into the Deep")

Photo: ABC

Season 2 of ONCE UPON A TIME continues on Sunday, November 25 at 8 p.m. ET/PT on ABC.

In "Into the Deep," Cora does everything in her power to steal the compass away from Mary Margaret and Emma in her quest to find the entrance to Storybrooke.

PREVIEW: ONCE UPON A TIME ("Child of the Moon")

Photo: ABC

Season Two of ONCE UPON A TIME continues on Sunday, November 11 at 8 p.m. ET/PT on ABC.

In "Child of the Moon," Ruby's fear about turning into a wolf during the first curse-free Storybrooke full moon is confirmed when one of the town's residents is viciously murdered, and Ruby is the prime suspect; Decker - aka King George - threatens to expose David as a shepherd, not a prince, and not fit to run the town as sheriff; and Leroy stumbles upon some treasure in the Storybrooke mine that could help bring Mary Margaret and Emma back into our world.

PREVIEW: ONCE UPON A TIME ("Tallahassee")

Photo: ABC

Season Two of ONCE UPON A TIME continues on Sunday, November 4 at 8 p.m. ET/PT on ABC.

In "Tallahassee," with the hopes of finding a magical compass that could help her and Mary Margaret get back to Storybrooke, Emma takes a journey with a not-too-trustworthy Captain Hook up a treacherous beanstalk in an attempt to steal the item from a murderous giant (Jorge Garcia, LOST).

PREVIEW: ONCE UPON A TIME ("The Doctor")

Photo: ABC

Season Two of ONCE UPON A TIME continues on Sunday, October 28 at 8 p.m. ET/PT on ABC.

In "The Doctor," while Regina continues to try and stop using her magic in an attempt to win back Henry's affections, she begins seeing what she believes is a ghost from her past; and when Mary Margaret and Emma discover a lone survivor from an ogre massacre, Emma begins to question whether or not he's telling the truth.