HalloVeen

In its original American broadcast, "HalloVeen" was seen by an estimated 1.69 million household viewers and gained a 0.6/2 ratings share among adults aged 18–49, according to Nielsen Media Research.[1] This was slight increase in viewership from the previous episode, which was watched by 1.68 million viewers with a 0.7/3 in the 18-49 demographics.[2] This means that 0.6 percent of all households with televisions watched the episode, while 2 percent of all households watching television at that time watched it. With these ratings, Brooklyn Nine-Nine was the third highest rated show on FOX for the night, behind The Mick and Lethal Weapon, sixth on its timeslot and fifteenth for the night, behind The Mick, The Mayor, Kevin (Probably) Saves the World, The Flash, Lethal Weapon, Law & Order True Crime, Fresh Off the Boat, Black-ish, NCIS: New Orleans, Bull, The Middle, NCIS, The Voice, and This Is Us.

"HalloVeen" received critical acclaim. LaToya Ferguson of The A.V. Club gave the episode an "A" grade and wrote, "The entire Halloween heist hinges on those involved outsmarting each other, and as part of that fun, it cheapens it if any of the characters are dumbed down to create that type of outsmarting. The past couple of Halloween episodes have remembered that, and 'HalloVeen' improves upon that recognition by making sure everyone available is able to do that. Seriously, even Scully and Hitchcock get to show off some brains here (and they do so toward Captain Holt of all people). Their brains are all related to their own perverted weirdo nature, but that's what they're good at, after all."[3] Liz Shannon Miller of IndieWire wrote, "If you were looking for further proof that 'Brooklyn Nine-Nine' is one of the best comedies on television, 'HalloVeen' was it. From the cold open of the episode, the show crackled with energy, letting the lighthearted heist competition that's become a yearly tradition drive the pitch-perfect interactions of the ensemble."[4]

Alan Sepinwall of Uproxx wrote, "Recency bias is always a dangerous thing, and it's been a while since I watched the first few heist episodes, but if 'HalloVeen' isn't my favorite of the tradition, it's vastly better than it has any business being five seasons in."[5] Caroline Framke of Vox wrote, "The Fox sitcom is reliably silly, warmhearted, and very funny, but it wasn't a stretch to assume that its October 17 episode would be particularly good. See, 'HalloVeen' is the fifth of Brooklyn Nine-Nine's annual Halloween episodes, which have centered on the detectives pulling off increasingly ridiculous heists to prove they can outsmart each other. Every single Halloween episode has been a season highlight, but 'HalloVeen' still managed to outdo all the rest thanks to some canny callbacks, a clever twist, and a very good dog."[6]