SpawnWorld

Here is the most precise list I've done after reading literally everything up to issue #100.

Let me know of any changes if you know them. This does not include the 1-shot books.

Curse of the Spawn #20-21 (First Hellspawn & Nyx debut)
Spawn: The Dark Ages #1-28
Medieval Spawn & Witchblade #1-3
Aria & Angela: Heavenly Creatures #1-2
Operation Knightstrike #1-3 (Al Simmons & Chapel debut)
Battlestone #1
Youngblood Strikefile #1-3: Chapel (Knightstrike disbanded)
Youngblood: Genesis #1 (Knightstrike becomes Youngblood)
Curse of the Spawn #12-14 (Jessica Priest)
Curse of the Spawn #15-16 (Abe joins Hell & Al becomes Spawn)
Spawn #1-7 (Spawn’s debut)
Curse of the Spawn #23-24 (Overt-kill rebuild)
Spawn #8-20
Spawn & Batman Book
Spawn Fan Edition (Vandalizer debut & Norse Hellspawn story)
Violator #1
Youngblood Strikefile #4
Spawn #21-22
Violator #2-3
Violator vs. Badrock #1-4 + Celestine #1-2
Spawn #23
Youngblood #7 + Team Youngblood #11 (Overt-kill’s Malfunctioning)
Spawn #24-26
Bloodstrike #8 + Youngblood #8 + Youngblood 10 + Extreme Sacrifice #1 + Prophet #10 + Extreme Sacrifice #2 (Death of Chapel arc)
Spawn #27-28
Angela #1-3
Spawn #29-32
Spawn: Bloodfeud #1-4
Angela & Glory: Rage of the Angels #1 + Angels in Hell #1 (Evil Celestine & Lucifer debut)
Spawn #33-39
Spawn & WildCATS #1-4
Spawn #40-52
Savage Dragon #30 (conclusion from #52 into #53)
Spawn #53-61
Cy-gor #1-6
Curse of Spawn #5-8 (Suture & Sam & Twitch)
Curse of the Spawn #9-10 (Angela’s Teleport)
Spawn #62
Curse of the Spawn #11 (Angela’s Teleport contd)
Curse of the Spawn #17-19 (Dergeus is free still)
Spawn #63-87
Sam & Twitch #1 (Back on the Force)
Spawn The Undead #1-9 (Spawn’s new power)
Spawn #88-100 (Death of Malebolgia)
a)Spawn 101 + Simony +102-175
Curse of the Spawn #26-28 (Dr. Marc Simmons debut)
Spawn #176-185 (Death of Al Simmons)
Spawn #186-230+ (New Spawn...on going)
The Curse of Spawn #1-4 + Blood & Salvation (Future)
b)Hellspawn #1-16 (alternatime timeline after issue #100) + Curse of the Spawn #22 (Zombie Spawn) & #25 (Angel)


Unkown spots: Spawn the Impaler #1-3, Curse of the Spawn #29 (End of Purgatory

Shit I haven't read yet but have been told don't go into the original series continuity anyway:

ALTERNATE SERIES:
Shadows of Spawn #1-3
Spawn: The Godslayer #1-9


BOOKS (Non-Canon):
Spawn & Batman: War Devil Book
Spawn: Blood & Shadows Book
Spawn: Architects of Fear Book
Spawn: Book of the Dead
Spawn: The Movie Book


OTHER CHARACTERS:
Sam & Twitch #2-26
Case Files: Sam & Twitch #1-25
Sam & Twitch: The Writer #1-4
The Creech: Rage Against Death #1-4
The Creech: Out for Blood #1-3

Great! Mind if I use this for my Wiki?

I assume you were asking Forever Knight, but just in case - fine by me