There's also the mysterious helicopter we've seen in Season 8, a skull with a pitchfork thrust into it, a bunch of creepy ravens, and a message scrawled on the gates: "Final warning".
"We're paying homage to some of the iconic moments from the graphic novel. Life is coming out of death. Nature's taking over, while other things are crumbling," said Kang.
The Whisperers bring a new kind of evil to Season 9
Watch the season 9 trailer above right to the end and something very creepy will startle you. As a horde of walkers troop past Eugene and Rosita, who are desperately trying to conceal themselves in what looks like a pool of mud, we clearly hear one mutter in a raspy tone: "Where are they?"
Walkers have not suddenly gained the ability to talk. But in season 9, set a year and a half after 'All Out War', we meet the Whisperers, a new group of scumbags that could be even worse than The Governor, the Scavengers, the Wolves, Negan and any other Walking Dead villains before them.
These guys cover themselves in the skin of the undead so they can walk among the zombies, getting right up close to their victims and attacking before they have time to realise what's happening. And then they place their heads on spikes outside their walls as a warning to all those who get too close.
So while the walkers themselves are in essence pretty dumb, this new ultra-terrifying breed of killers that walks among them is something else. And it plays to the theory of humans being the biggest evil of all that we've seen in recent seasons.
Samantha Morton has been cast to play the lead Whisperer, Alpha, with Ryan Hurst as Beta. Together with her crew, Alpha could pick off some of our favourite characters.
Who dies in The Walking Dead Season 9?
We already know that season 9 will see Darryl take the lead as it is the final season for both Maggie and Rick, but not how they will ultimately meet their maker - or if they will. Maggie most likely will not die, given that Lauren Cohen has been booked for occasional appearances in future shows.
Rick has also confirmed he will be returning in Season 10, but as a director rather than an actor.
It's been apparent for a while now, and again in the teaser video above, that there is friction between the two following Rick's decision to keep Negan alive. After all, this guy killed Maggie's beloved Glenn. And it was all Jesus could do to stop her slaughtering the Saviors in season 8.
In the comic books on which the TV series is loosely based, it's Negan who eventually puts a stop to Alpha (what could this mean for his imprisonment at Alexandria?) - but not before the Whisperers manage to kill King Ezekiel and put his head on a stick. We really hope new showrunner Angela Kang doesn't decide now is the time to start following the comics.
Other Walking Dead Season 9 rumours
The first five minutes of 'A New Beginning', the first episode in Season 9, reveal a glimpse of life after All Out War:
Shane Walsh, Rick's ex-police partner whose dalliances with his wife Lori ultimately led to his death, is back. Show bosses have been forced to confirm this after Jon Bernthal was spotted on location, but exactly how this will work is not known. It's likely that he'll feature in Rick's flashbacks.
Also returning in season 9 are Michonne, Carol, Tara, Rosita, Eugene, Father Gabriel, Aaron, Jesus, Enid, Ezekiel, Jerry, Jadis and Negan. As well as new cast members Samantha Morton and Ryan Hurst, Eleanor Matsuura, Nadia Hilker, Dan Fogler, Brett Butler, John Finn, Rhys Coiro, Zach McGowan and Lauren Ridloff will be joining the show, potentially alongside a new pet for Darryl: a dog.
While the group are seen establishing a new community at Alexandria, things could go awry again. A teaser poster leaked by AMC shows the Capitol Building in the background, suggesting Rick and friends will be upping sticks and heading to Washington DC.
Could this have something to do with the helicopter we saw in season 8, and again in the trailer at the top of this page? Fans think it could be owned by new community the Commonwealth, especially after we met Georgie, its suspected leader in season 8, and potentially linked to the 'New World Order' story arc in the comics. Jadis, the sole surviving Scavenger and now within Rick's fold, certainly seems to know who it belongs to.
Among all the gory bits, there has been some talk of good news: Carol and Ezekiel, who are now officially an item, might be getting married in season 9 - more reason to hope his head will not end up on a stick. Regardless, it's looking like the Darryl-Carol pairing fans have long hoped for is still just wishful thinking.