Dungeons & Dragons has been around since 1974, when Gary Gygax and Dave Arneson created it as an alternative to traditional tabletop wargames. Every player made a fantasy character and then the dungeon master guided them through a story, testing their mettle against monsters and NPCs.
Some DMs built their own stories from the ground up, but D&D also has a long history of releasing pre-stories and settings for characters to explore. They vary wildly in theme, tone, and—frankly—quality, but here are the best of the best.
10 The Isle of Dread
This classic adventure was first published in 1981 and is probably one of the most widely circulated D&D adventures in history. This is because a copy of the adventure was included in the D&D Expert Set. This set gave players rules for playing characters from level 4 through 14. Along with this new scope, The Isle of Dread gives players and dungeon masters a completely new type of gameplay: wilderness exploration.
Most D&D adventures up to this point were of the dungeon-crawling variety. The Isle of Dread, however, was a vast tropical island for characters to explore. The overall plot isn't very deep, but what sets this module apart is the freedom players have. They're welcome to go anywhere on the island, encounter several civilizations (of human and nonhuman races), and battle against new monsters like kopru and even dinosaurs.
9 Expedition to the Barrier Peaks
When you picture a Dungeons & Dragons game, you probably have a very specific aesthetic in mind. Classic sword and sorcery fare, complete with pseudo-medieval Europe vibes. What made Expedition to the Barrier Peaks so special was it took that classic feeling and through it headfirst into a science fiction setting.
Characters in this adventure set off into the mountains to find the source of the monsters plaguing a nearby duchy. Instead of a cave, what they find is the entrance to a crashed spaceship, still full of semi-functional robots and other alien creatures. This makes for such a unique and memorable adventure, many old-school players still count it among their favorites.
8 Castle Amber
The second adventure designed for use with the Expert Set, this module embroils characters in the drama of the Amber family. The party is drawn to a castle surrounded by a thick, deadly mist. The mist is the results of a curse laid by the dead wizard Stephen Amber, as a punishment for his family for murdering him. Of course, it also traps the players characters. The only way to escape is to explore the castle, frequently encountering the rest of the Amber family who seem decidedly...off.
The chaotic nature of the module didn't appeal to everyone. Some players considered it too random, where a literal roll of the dice could be deadly for the entire party. The module has been described as similar to the work of both Edgar Allen Poe and Lovecraft. Despite the brutal difficulty, many still love the adventure for the atmosphere of the setting.
7 The Sinister Secret of Saltmarsh
The first of a trilogy of modules written by Dave J. Browne and Don Turnbull, The Sinister Secret of Saltmarsh was an introduction to a brand new underwater campaign. Players explore the sinister haunted mansion on the outskirts of a town called Saltmarsh and learn the secrets of the evil alchemist that lived there.
The module incorporated horror elements, but framed it as more of a mystery players were trying to solve. It placed a lot of focus on investigation and problem-solving, instead of run-of-the-mill dungeon crawling.
6 Desert of Desolation
One of the first adventures written by Tracy Hickman (and partially by his wife Laura), the Desert of Desolation trilogy collected the stand alone adventures Pharoah, Oasis of the White Palm, and Lost Tomb of Martek. The Hickmans originally published the first adventure privately, but when they hit some financial trouble, they decided to sell them to D&D publisher TSR. TSR instead decided to hire Tracy on as a game designer.
The Desert of Desolation module was presented and formatted so excellently that it became the standard way to present encounters for later third edition adventures. Also, while the first adventure Pharoah was more of a typical dungeon crawl, the sequels established backstory and atmosphere that elevated the entire series.
5 Queen of the Spiders
Commonly referred to as a "supermodule," Queen of the Spiders collects a grand total of seven previous adventures in a massive campaign. It starts with the modules comprising Against the Giants, which you might be familiar with if you picked up the recent 5e book Tales from the Yawning Portal.
At the end of that module, players are introduced to the plotting drow priestess Eclavdra, and the following adventures chronicle the adventurers' descent into the Underdark. It all culminates in the lair of the drow's patron goddess, Lolth. This series of adventures introduced both drow and the Underdark into D&D canon, and both remain popular elements of many campaigns to this day.
4 The Temple of Elemental Evil
Gary Gygax published a module in 1979 called The Village of Hommlet, which was a fully detailed village where a party could base an entire campaign. Six years later, a follow-up to the adventure added the titular Temple of Elemental Evil, a five-level dungeon with over 200 possible encounters.
The adventure became the new standard for "dynamic dungeons." Not simply dungeon crawls, The Temple of Elemental Evil was a dungeon chock full of intelligent monsters and NPCs. These NPCs would react to incursions by the player characters, fortifying and strategizing as necessary. Not to mention there were a total of four factions competing for control of the temple that players needed to keep tabs on, making for an enthralling web of conspiracy.
3 Keep on the Borderlands
Perhaps one of the first adventure modules players encountered, thanks to its inclusion in the D&D Basic Set, it helped define the iconic picture of the game. Players were based at the eponymous Keep and could make multiple forays into the nearby Caves of Chaos.
The caves were notoriously deadly and unpredictable, and notably didn't scale based on depth. Party-killing encounters could be found on the very first level alongside much easier goblins and kobolds. While it might not have depth later adventures would adopt, it can't be ignored as the archetype for every dungeon crawl to follow.
2 Tomb of Horrors
Here it is. The most infamous module in the history of D&D. Created by Gygax specifically to put overpowered characters in their place, Tomb of Horrors is not designed to be bested.
Supposedly a puzzle dungeon, most of the "puzzles" are so opaque that there's little way to know what you've done wrong until you're already rolling a new character. The very definition of a meat grinder, you might want to have several reserve character sheets if your DM whips out this terrible tomb.
This is probably the most iconic and well-known module in all of D&D. Written by Tracy and Laura Hickman, Ravenloft not only created the campaign setting of the same name, but also introduced the most recognizable D&D villain of all time: Strahd von Zarovich. It has been adapted and revised numerous time in different editions, including the most recent Curse of Strahd adventure for 5th Edition.
It was considered a breakthrough in adventure design. Not only did it include a minutely detailed castle map for players to explore, but it introduced an interesting fate mechanic for the plot. The player characters get their fortunes told at the beginning of the adventure, and the DM will actually perform the card reading, introducing randomness to the plot that let even repeat players experience something new each time.