My attempt to advance some publications for 1e:
Monster Manual (1e): The original AD&D rulebook, and the original dedicated monster book.
Players Handbook (1e): When AD&D truly became its own game, establishing the template for the modern era.
Dungeon Masters Guide (1e): The original guidebook for DMs, full of Gygaxian wonder.
A1-4: Scourge of the Slavelords (1e): You beat up slavers!
C2: The Ghost Tower of Inverness (1e): Noted for making players think.
D1-2: Descent Into the Depths of the Earth (1e): The first modules to feature the drow, and the sequel to...
G1-2-3: Against the Giants (1e): One of AD&D's earliest and most famous adventure paths.
I6: Ravenloft (1e): An enduring classic that inspired an entire setting, and showed a new way to play the game.
L1: The Secret of Bone Hill (1e): Quoting
@Lanefan: "By TSR standards it's a masterclass in non-linear dungeon design".
N1: Against the Cult of the Reptile God (1e): A more investigative adventure for beginners.
Q1: Queen of the Demonweb Pits (1e): The finale of the storyline started by the G and D series, pitting the heroes against Lolth herself.
S1: Tomb of Horrors (1e): The original killer dungeon. YMMV on whether it's famous or infamous...
S2: White Plume Mountain (1e): Often cited as one of D&D's great "funhouse" dungeons.
S3: Expedition to the Barrier Peaks (1e): D&D's most famous blend of SF and fantasy.
S4: The Lost Caverns of Tsojcanth (1e): The grand finale of the S series.
T1: The Village of Hommlet (1e): The iconic place for 1e adventures to begin.
T1-4: The Temple of Elemental Evil (1e): The expansion of the above, featuring a true mega-dungeon.
U1: The Sinister Secret of Saltmarsh (1e): The original haunted house adventure.
UK1: Beyond the Crystal Cave (1e): The first in a series of British adventures, which encourages non-violent solutions!
WG4: The Forgotten Temple of Tharizdun (1e): A particularly Lovecraftian sort of dungeon crawl.
Battlesystem (1e): Bringing D&D back to its wargame roots.
The Book of Lairs (1e): Looking for a bunch of short adventure ideas for any campaign? Check this out!
Deities & Demigods (1e): The second attempt at bringing real-world mythology into D&D, and the one most fondly remembered.
Fiend Folio (1e): The odd middle child of the 1e monster books, and the first major UK contribution to the game!
Manual of the Planes (1e): D&D's first comprehensive treatment of the planes.
Monster Manual II (1e): The third and final monster book for 1e. Among other things, it gave us modrons!
Oriental Adventures (1e): D&D's first attempt at an Asian-themed setting.
The Rogues Gallery (1e): Includes early writeups for some of the game's original iconic NPCs!
Unearthed Arcana (1e): Gygax's final contribution to official D&D.
The World of Greyhawk Fantasy World Setting (1e, 1980, Folio): The original campaign setting, and for many the definitive version of Greyhawk.
World of Greyhawk Fantasy Game Setting (1e, 1983): Except for the Greyhawk fans who prefer this more comprehensive version.
Greyhawk Adventures (1e, 1988): The first post-Gygax take on Greyhawk, and the last for 1e.
Dragonlance: Dragons of Despair (1e, DL1): The original Dragonlance adventure, helping establish a whole new approach to D&D games.
Dragonlance Adventures (1e): The original all-in-one take on the Dragonlance setting.
Forgotten Realms Campaign Set (1e): The original version of the Realms, and for many the best.
Kara-Tur: The Eastern Realms (1e): The most detailed exploration of the Eastern part of the setting.