Seven, the beloved Belgian Malinois who played Daryl Dixon's dog on The Walking Dead, has died. On Thursday, network AMC and the official Walking Dead social media accounts announced the animal actor's death with a tribute to the zombie drama's "best boy." A cause of death was not disclosed. Seven appeared in 25 episodes of the series since the season 9 episode "Stradivarius" in 2018, which introduced the dog -- named Dog -- as the canine companion of Daryl (Norman Reedus).

"Gonna miss u Seven," Reedus wrote on Instagram Stories. "Best TV buddy ever."

? NEWS: According to Norman Reedus' Story on Instagram- Sadly, Dog from #TheWalkingDead has sadly passed away ??? pic.twitter.com/EOgGF62kvV

-- Aaron (@AaronsArmTWD) June 13, 2024

The dog was named "Dog" by his original owner, Leah (Lynn Collins), Daryl's lover when he spent six years living alone in the woods while looking for Rick Grimes (Andrew Lincoln). When Leah disappeared from her cabin in the woods in the season 10 episode "Find Me," Daryl adopted Dog as his own.

Reedus spent years asking the Walking Dead producers to give Daryl a dog. During a visit to the Georgia set in 2018, Reedus gushed to ComicBook about working with Seven.

"It's so good," Reedus exclusively told ComicBook at the time. "I love it. I think he's the smartest cast member we got. We just did a scene the other day that ended up being the opposite of what it was supposed to be because the dog just wanted to do something else, and it came out so much better. He'll probably be running the show. It's great! I love it. He loves me, too."

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Dog's role came about as a way to "show the state that Daryl's in" after the missing Rick was thought dead, showrunner Angela Kang explained in a 2018 interview. "And I thought that it would be great that he's been off for a while after Rick's presumed death. Daryl just went off. And Daryl is somebody who hunts and goes about and does things, and it seemed like a dog is a good companion. It shows that there's still a desire for him to have a connection somehow. And so the dog is his faithful companion."

Seven drew praise from David Boyd, who directed Dog's origin story episode. "Find Me" flashed back to Daryl's first meeting with the zombie-fighting dog as a seemingly stray pup (played by a younger dog actor, named Carl).

"I won't stop talking about Dog. That animal is fantastic," Boyd told HuffPost in a 2021 interview. "[Seven] has a brain, and he's got an acting spirit. In prep, you go, 'This dog is never going to do any of it,' right? You read the script and you go, 'OK, he goes there and stops there and he barks there. It's never going to happen. It's going to take 19 hours to get one thing out of this dog.' But no. Take one. Boom! We go, OK. We look at each other and say, 'Well, do we need another take?'"

"There's a little bit scripted where at the beginning of the episode, dog runs right at camera and is supposed to come to a screeching halt and kick up some dust. And we read that and go, 'Well, that's never gonna happen,' and take one. Perfect. We just said, 'Well, what the hell? Now we're an hour ahead. Let's do another take.' And same thing. Perfect. Exactly right. Excellent," Boyd continued, adding that Seven was capable of performing even the most complicated commands. "[Seven's trainers] go, 'Well, I don't know.' Damned if that dog didn't do it. Every single bit of it. That dog can perform for four minutes and just keep going. That's amazing. I love him."

Collins also fondly remembered working with her animal co-star, telling Den of Geek in 2021: "[Seven's] actually an older guy. He's not a pup. And so he is really comfortable on set and really easy to work with and super loving and the trainers are incredible. So it was really easy to just sit with him and pet him and love on him. I think literally at one point they were like, 'Lynn, stop playing with him. He's not going to be able to focus.' That's how sweet and loving this dog was."

Seven's Dog last appeared in The Walking Dead's "Rest in Peace" series finale in November 2022.