One of the most suspicious possible Watchers wasn’t introduced until toward the end of the series. Former English teacher Roger Kaplan has one of the most intense obsessions with 657 Boulevard, plus he has a weird quirk where he writes letters to houses. Oh, and to top it all off, the first Watcher letters appeared at a house he was sending love letters to for years... right after his love letters ceased.

Roger claimed to have no involvement in the Watcher scandal, but he never really gave any solid alibis. Not to mention, the Watcher’s hunger for “young blood” could allude to Roger divorcing his wife to marry a student.

If we’re talking about sketchy neighbors, nobody is weirder than the Winslows. Not only does Jasper’s penchant for sneaking into 657 Boulevard make him incredibly sus, but his sister Pearl also has an inexplicably intense interest in preserving the house.

Let’s not forget about the tunnels beneath 657 Boulevard that seem to connect the house to its neighbors. And who lives right next door? The Winslows. After the police found female DNA on one of the Watcher letters, there was a lot of hints that the perpetrator could be a man and woman working together. Pearl and Jasper seem to fit the bill perfectly.

Joe Graff is definitely up to something nefarious, but it doesn’t seem like he’s working alone. The final few episodes of The Watcher all but confirmed he was in cahoots with the Winslows, suggesting that the three of them were all working together as the Watcher. We already know Joe is a murderer and used to live in 657 Boulevard, but it’s not super clear why he’d return to scare off a seemingly random new family. Still, there’s no way he wasn’t at least somewhat involved in terrorizing the Brannocks.

Dakota may seem like a sweet, innocent kid, but when you really start to think about it, he also had means, motive, and tons of opportunity to pull off all the Watcher hijinks. The finale saw Dakota putting an advertisement for his security business in the mailbox of the new homeowners, dropping a little hint that he may have done all this to cash in on all the money the Brannocks paid him for security.

On top of that, he often offered to watch the Brannocks’ house for them, and always seemed to be hanging around somewhere. Oh, and let’s not forget his screen name in his video game is literally “The Watcher.” It didn’t seem like Dakota was a bad guy, but there sure are a lot of knocks against him...

Mo and her husband Mitch seemed to fit the bill for someone who calls themself the Watcher right off the bat. The couple would constantly stare at 657 Boulevard in their lawn chairs, not to mention the rumors they belonged to a blood-sucking cult. TBH though, there isn’t much concrete evidence to hold against Mo, just that she’s super creepy and seems way too into 657 Boulevard.

At first, Andrew Pierce seems like a fellow victim of the Watcher, but the previous 657 Boulevard homeowner could also actually be the anonymous letter-writer. At the very end, Theodora Birch suggested that Andrew actually experienced mental health issues and addiction, making him highly suggestible to believing falsehoods. Although Theodora’s assessment may have been a lie, it still points to the possibility that Andrew lost it when he saw a new couple move into his old house and began terrorizing them out of spite.

Don’t count out Detective Chamberland. The police chief was strangely unhelpful in assisting the Brannocks unmask the Watcher, to the point of even refusing to help them anymore in the end. He also had a motive to scare them out of the house, since he was dating realtor Karen Calhoun, who swooped in to buy the home once the Brannocks finally left.

He looks even worse after Karen begins getting terrorized by the Watcher shortly after she broke up with him.

OK, Theodora may seem like the one character to rule out as being the Watcher since her big confession was pretty much confirmed to be false. But still — everyone’s a suspect in this show. Theodora’s story about being the previous 657 Boulevard homeowner who became the Watcher out of spite for the Brannocks seemed to add up... until Mo revealed she had never lived in the house. But hey, Mo isn’t the most trustworthy source, after all. Maybe Theodora purposefully left a hole in her otherwise true story as her last mastermind trick to throw the Brannocks off the scent.

That brings me to the final theory: Could Dean and Nora have been behind the letters all along? Dean admitted to sending some of the letters, and it was clear he was experiencing some kind of mental health crisis at 657 Boulevard. Where it all falls apart is motive — sure, he might have wanted a reason to back out of his multi-million-dollar investment after losing out on his promotion, but it doesn’t seem like he’d go so far as to ruin his family’s lives for it.

Interestingly enough, the actual couple the story is based on, Derek and Maria Broaddus, were at the center of a similar conspiracy theory: Once their story blew up in 2018, they became pariahs in Westfield, as most of the residents accused the couple of fabricating the story. Although Broadduses denied the rumors that they were involved in the letter-writing to The Cut, the Netflix show may have seen this adaptation as an opportunity to nod to that theory.