Warning: There are spoilers ahead.

Sunday night's "Game of Thrones" finale was probably one of the most jam-packed episodes we've seen in a while focusing on multiple story arcs to tie up a lot of loose ends from season 4.

However, there's one very big loose end the series has yet to address.

Final warning before huge spoilers.

While the ending shots of season 4 showed Arya Stark sailing away on a ship, many diehard fans of the book thought they may see the return of a favorite character teased.

In season 3, Catelyn Stark was murdered alongside her son Robb and his pregnant wife.

Her body then gets tossed into a river after she's killed.

Readers of the book know that three days later Lady Stark gets resurrected and is brought back as Lady Stoneheart.

She can't speak (her throat is visibly damaged from getting slashed), she's covered in scratches, and a lot of her hair is gone. She's pretty grotesque.

But as much of a Frankenstein character Stoneheart may appear, she's a completely different character out to seek revenge on everyone who betrayed both her and her son. 

For anyone who may have been disappointed, actress Michelle Fairley, who plays Catelyn, was not signed on for season 4 of "Game of Thrones."

Fairley has actually been appearing on the new "24: Live Another Day" mini-series.

Some fans may have expected a hint at Lady Stoneheart after "Game of Thrones" actress Lena Headey recently posted a photo of a series of rocks on Instagram in the shape of a heart with the caption, "My stone heart."

Headey previously gave another hint on Instagram about an upcoming plot point.

When Sunday's episode aired, it even looked as if fans might get the scene. 

In the books, Brienne of Tarth comes across the resurrected Lady Stark after fighting a man posing as The Hound. 

"Game of Thrones" showrunners David Benioff and Dan Weiss threw us a curveball by having Brienne fight the actual Hound.

So where's Lady Stoneheart? 

Don't worry fans. We're sure it's coming. And, we're sure that when it does happen (not if) that it will be awesome and worth the wait.

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SEE ALSO: Everything we know so far about season 5 of "Game of Thrones"

AND: Why "Game of Thrones" probably set its finale on Father's Day