Warning: This article contains SPOILERS for The Walking Dead season 9 finale.
Here's who was on the radio in The Walking Dead season 9 finale. This was a different finale to what viewers are used to. Rather than wait until next season to see who was killed off on The Walking Dead, which is something the producers opted not to do with The Walking Dead's fair episode this year, viewers are left on a note wondering who's on the other end of Hilltop's radio.
In The Walking Dead season 9 finale, audiences see the aftermath of the fair and having almost a dozen people killed by Alpha and the Whisperers. So, instead of diving into another death-heavy episode or one that takes place immediately after "The Calm Before", The Walking Dead season 9 finale, "The Storm", places an emphasis on survival. But at the end of the episode, when everyone's at Hilltop or back in Alexandria, Ezekiel and Judith communicate over a radio that Eugene, Gabriel, and Rosita tried to set up throughout season 9. It's only after they're done talking that audiences hear someone else come on the radio.
After Ezekiel walks away from the radio in The Walking Dead season 9 finale, "The Storm", the camera lingers on it for a few moments longer and that's when audiences hear what sounds like a female voice saying, "Hello? Hello? Calling out live on the open air. Is anybody out there?" After that, the camera cuts to black. It's an interesting choice having the radio be the big mystery at the end of season 9 rather than having the finale be the fair. But just who's the person on the radio?
While it's not expressly confirmed who's on the other end of the radio in The Walking Dead season 9 finale, given what happens in The Walking Dead comics, that person on the radio must be Stephanie, a member of the Commonwealth community. In the comics, Eugene uses the radio and starts communicating with Stephanie, and eventually, they decide to bring their communities together. But while Alexandria is quite big for existing in the apocalypse, the Commonwealth is even bigger - a community with over 50,000 people that also makes up an army, sports arenas, and even concerts. Bringing in the Commonwealth in The Walking Dead season 10 will take the series into its next story arc, the "New World Order".
What's important is that, in addition to helping out the current communities and potentially aiding them in resolving their Whisperer issues, the Commonwealth is also where Michonne discovers her daughter is still alive. Michonne has a son on The Walking Dead TV show instead of a daughter, and unfortunately, it was previously confirmed that her son is still dead. However, that doesn't mean Michonne won't discover that Rick Grimes is still alive, which would open a door for Danai Gurira's planned exit in season 10. But audiences will have to wait until The Walking Dead returns later this year to find out if any of that will happen.