The last scene of The Walking Dead Season 9 ended with a twist: a mysterious voice coming over a radio, signaling that Hilltop will either be meeting someone new or getting reacquainted with an old friend in Season 10.

In the scene, Ezekiel (Khary Payton), from his new home at Hilltop, was talking to Judith (Cailey Fleming) on the radio about their hopes for the future. Seconds after he signed off and walked out of the room, a different voice came over the radio. It was fuzzy and indistinct, as if it were coming from very far away. The episode's closed captions for the scene said, "Woman: 'Hello? Hello? Calling out live on the open air. Is anybody out there?'"

We obviously won't find out until Season 10, but we have some theories about who it might be.

The Walking Dead Went Man vs. Wild for Its Season 9 Finale

The most obvious possibility is Maggie (Lauren Cohan), Hilltop's missing leader, who is off learning the finer points of colony administration from Georgie (Jayne Atkinson), the woman we briefly met in Season 8 who gave Hilltop a book of instructions on how to build a medieval society. Maggie has been away for the whole time The Walking Dead has been in its current timeline, and she has not responded to letters informing her of the leaderless current situation at Hilltop. Maybe if she can get ahold of someone when they come back into the radio room, she'll find out that Jesus (Tom Payne) and Tara (Alanna Masterson) are dead, and she'll decide to come home and lead her reeling community. Lauren Cohan, who left to focus on her new show Whiskey Cavalier, may possibly return to The Walking Dead in a limited capacity in Season 10.

Another possibility is that it's Jadis (Pollyanna McIntosh), or someone connected to the group that took her and Rick (Andrew Lincoln) away, finally getting in touch after all these years. We know Danai Gurira will be departing in Season 10, and maybe this call will be the catalyst to set her off on her journey to reunite with Rick in the upcoming Walking Dead movies.

With regards to the voice on the radio, executive producer Angela Kang told Comicbook.com, "I don't want to give too much away about that, but I will say we will get answers to that question within Season 10. It's always interesting for us to introduce new people into our world, and the different ways they come in, so that will definitely be an important aspect of the story going forward."

Comicbook.com pointed out that the "calling out live over the open air" line is taken from the comics. In issue #151, Eugene is messing around with a radio for no particular reason, and his call over the open air gets a response from Stephanie, who is from the Commonwealth, a more advanced community based in Toledo, Ohio that becomes very important as characters, including Michonne, travel from Alexandria to there. On the show, Georgie might be from the Commonwealth, as there was a sign pointing towards Toledo in the bridge construction workers' camp early in Season 9, though neither Georgie's home nor the Toledo sign have been explained. It's also possible that Jadis and Rick went to the Commonwealth, as the Commonwealth has an army with pre-apocalyptic technology, such as helicopters. So signs point to it being a voice from the Commonwealth, though who exactly remains to be seen.

Who do you think is on the radio?

PHOTOS: Badass Women of The Walking Dead

Danai Gurira and Lauren Cohan, <em>The Walking Dead</em>Danai Gurira and Lauren Cohan, The Walking Dead

The Walking Dead will return for Season 10 in the fall on AMC.