So many regular series, since the dawn of time, have had Halloween episodes, which I don't consider "specials." Still, I suppose I might as well at least list some of them, in passing. At least the ones I personally remember (even vaguely) seeing; surely there have been many I've seen that I've forgotten, and many more that I've never seen at all. I'm not going to be saying much of anything about the episodes here, so perhaps you'll find the links useful. But for some of the episodes, I may have said a bit about them in my annual Halloween journals. (Note: most of these episodes originally aired on or near Halloween, but some may have aired at other times of year. The important thing is whether Halloween itself is pertinent to the episode's plot.)
3rd Rock from the Sun
Season 3: Scaredy Dick (Amazon; Halloween Specials Wiki; IMDb)
Aaron Stone
Season 1: Dreamcast (IMDb)
American Dad!
Season 6 (or 7?): Best Little Horror House in Langley Falls (Amazon; Halloween Specials Wiki; IMDb; Wikia; Wikipedia)
American Dragon: Jake Long
Season 1: The Halloween Bash (Halloween Specials Wiki; IMDb; Wikia)
American Horror Story
Season 1: Halloween, Parts 1&2 (Amazon; A.V. Club; IMDb; TV Tropes; Wikia; Wikipedia)
Season 3: Fearful Pranks Ensue (Amazon; A.V. Club; IMDb; TV Tropes; Wikia; Wikipedia)
American Housewife
Season 1: Westport Zombies (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 2: Boo-Who? (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 3: Trust Me (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 4: The Maze (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Angel
Season 5: Life of the Party (Amazon; IMDb; TV Tropes; Wikia; Wikipedia)
Aqua Teen Hunger Force
Season 2: The Shaving (Adult Swim; Amazon; Halloween Specials Wiki; IMDb; Wikia) When I think of Halloween in regards to ATHF, I generally think of Meatwad trick-or-treating in an Elvis costume... except it wasn't Halloween when he did that (in the season 1 episode "MC Pee Pants"). This episode was definitely Halloween, though. And there may be others, I dunno.
Ben and Kate
Season 1: Scaredy Kate (Amazon; A.V. Club; IMDb)
The Big Bang Theory
Season 1: The Middle Earth Paradigm (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 5: The Good Guy Fluctuation (Amazon; A.V. Club; IMDb; Wikia)
Season 6: The Holographic Excitation (Amazon; A.V. Club; IMDb; Wikia)
Blackish
Season 1: The Prank King (Amazon; A.V. Club; IMDb; Wikia)
Season 2: Jacked o' Lantern (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; Wikia)
Season 3: The Purge (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 5: Scarred for Life (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 6: Everybody Blames Raymond (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Bless the Harts
Season 1: Cremains of the Day (Amazon; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 2: Dead Mall (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Bob's Burgers
Season 3: Full Bars (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
Season 4: Fort Night (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
Season 5: Tina and the Real Ghost (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
Season 6: The Hauntening (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
Season 7: Teen-A-Witch (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
Season 8: The Wolf of Wharf Street (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 9: Nightmare on Ocean Avenue Street (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 10: Pig Trouble in Little Tina (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 11: Heartbreak Hotel-oween (Amazon; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 12: The Pumpkinening (Amazon; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 13: Apple Gore-chard! (But Not Gory) (Amazon; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Boston Legal
Season 2: Witches of Mass Destruction (IMDb)
Brooklyn Nine-Nine
Season 1: Halloween (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 2: Halloween II (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 3: Halloween III (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 4: Halloween IV (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 5: HalloVeen (Amaon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Buffy the Vampire Slayer
Season 2: Halloween (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
Season 4: Fear, Itself (Amazon; A.V. Club; IMDb; TV Tropes; Wikia; Wikipedia)
Season 6: All the Way (Amazon; A.V. Club; IMDb; TV Tropes; Wikia; Wikipedia)
Castle
Season 2: Vampire Weekend (Amazon; A.V. Club; Castle Fans; Halloween Specials Wiki; IMDb; Wikia)
CBS Storybreak
Season ?: The Monster's Ring (HalloweenSpecials.net; IMDb)
Cheers
Season 3: Fairy Tales Can Come True (Halloween Specials Wiki; IMDb; Paramount+; Wikia)
Season 10: Bar Wars V: The Final Judgment (Halloween Specials Wiki; IMDb; Paramount+; Wikia)
The Cleveland Show
Season 2: It's the Great Pancake, Cleveland Brown (Amazon; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
Season 3: Nightmare on Grace Street (Amazon; Halloween Specials Wiki; IMDb; Wikia; Wikipedia)
Season 4: Escape from Goochland (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Community
Season 1: Introduction to Statistics (Amazon; A.V. Club; IMDb; TV Tropes; Wikia; Wikipedia)
Season 2: Epidemiology (Amazon; A.V. Club; IMDb; TV Tropes; Wikia; Wikipedia)
Season 3: Horror Fiction in Seven Spooky Steps (Amazon; A.V. Club; IMDb; TV Tropes; Wikia; Wikipedia)
Season 4: Paranormal Parentage (Amazon; A.V. Club; IMDb; TV Tropes; Wikia)
The Cosby Show
Season 2: Halloween (Amazon; Halloween Specials Wiki; IMDb; Wikia 1 Wikia 2)
Season 4: Cliff's Mistake (Amazon; Halloween Specials Wiki; IMDb; Wikia 2)
Danny Phantom
Season 1: Fright Night (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Dead Like Me
Season 2: Haunted (Amazon; IMDb; Wikia)
Desperate Housewives
Season 8: Witch's Lament (Amazon; Halloween Specials Wiki; IMDb; Wikia; Wikipedia) The series has done other Halloween episodes, but this is the only one I clearly remember. Sort of.
Don't Trust the B in Apt. 23
Season 2: Love and Monsters... (Amazon; A.V. Club; IMDb)
Dr. Quinn, Medicine Woman
Season 2: Halloween (Amazon; Halloween Specials Wiki; IMDb; Wikia) The show did a couple other Halloween episodes, but this is the only one I remember.
Dwight in Shining Armor
Season 4: The Draugar (BYUtv; IMDb)
Eastwick
Season 1: Bonfire and Betrayal (IMDb)
Eerie, Indiana
Season 1: America's Scariest Home Video (Amazon; Halloween Specials Wiki; IMDb)
The Emperor's New School
Season 1: The Yzma That Stole Kuzcoween/Monster Masquerade (Halloween Specials Wiki; IMDb; Wikia 1/2)
Even Stevens
Season 2: A Very Scary Story (Amazon; Disney+; Halloween Specials Wiki; IMDb; Wikia)
Everybody Loves Raymond
Season 3: Halloween Candy (Amazon; Halloween Specials Wiki; IMDb; Wikia) The cool thing about this episode is Frank dressing up as Frankenstein's monster... I mean, it's cool if you're a fan of Young Frankenstein.
Evil
Season 1: October 31 (Amazon; IMDb; Paramount+; TV Tropes; Wikia)
Family Guy
Season 9: Halloween on Spooner Street (Amazon; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
Foster's Home for Imaginary Friends
Season 5: Nightmare on Wilson Way (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Frasier
Season 5: Halloween (Amazon; Halloween Specials Wiki; IMDb; Paramount+; Wikia)
Freaks and Geeks
Season 1: Tricks and Treats (A.V. Club; IMDb; This Was Television; Wikia)
Fresh Off the Boat
Season 2: Miracle On Dead Street (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; Wikia)
Season 3: Louisween (Amazon; Halloween Specials Wiki; IMDb; TV Tropes; Wikia)
Season 4: It's a Plastic Pumpkin, Louis Huang (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 5: Workin' the 'Ween (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 6: Hal-Lou-Ween (Amazon; Halloween Specials Wiki; IMDb; Wikia)
The Fresh Prince of Bel-Air
Season 4: Hex and the Single Guy (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Futurama
Season 2 (or 3?): The Honking (Amazon; A.V. Club; IMDb; Infosphere; TV Tropes; Wikia; Wikipedia)
(Not really a Halloween episode, but it aired less than a week after Halloween 2000, and it has a very Halloween-appropriate plot.)
Gabby Duran and the Unsittables
Season 2: Beware the Fright Master! (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Ghosted
Season 1: Bee-Mo (Amazon; A.V. Club; IMDb)
Girl Meets World
Season 1: Girl Meets World of Terror (Amazon; Disney+; Halloween Specials Wiki; IMDb; Wikia)
Season 2: Girl Meets World of Terror 2 (Amazon; Disney+; Halloween Specials Wiki; IMDb; Wikia)
Glee
Season 2: The Rocky Horror Glee Show (Amazon; A.V. Club; FOX; IMDb; Wikia; Wikipedia) I don't recall if this was set around Halloween, but it aired around then, and the episode is Halloween-ish.
Grimm
Season 2: La Llorona (Amazon; A.V. Club; IMDb; Wikia)
Highway to Heaven
Season 2: The Devil and Jonathan Smith (IMDb)
Home Improvement
Season 2: The Haunting of Taylor House (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 3: Crazy for You (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 4: Borland Ambition (Amazon; IMDb; Wikia)
Season 5: Let Them Eat Cake (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 6: I Was a Teenage Taylor (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 7: A Night to Dismember (Amazon; Halloween Specials Wiki; IMDb; Wikia)
Season 8: Bewitched (Amazon; Halloween Specials Wiki; IMDb; Wikia)
How I Met Your Mother
Season 1: Slutty Pumpkin (Amazon; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
Season 6: Canning Randy (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
Season 7: The Slutty Pumpkin Returns (Amazon; A.V. Club; Halloween Specials Wiki; IMDb; TV Tropes; Wikia; Wikipedia)
iCarly
Season 1: iScream on Halloween (Amazon; Halloween Specials Wiki; IMDb; Wikia)