This is a list of Advanced Dungeons & Dragons 2nd edition monsters, an important element of that role-playing game.^[1][2][3] This list only includes monsters from official Advanced Dungeons & Dragons 2nd Edition supplements published by TSR, Inc. or Wizards of the Coast, not licensed or unlicensed third-party products such as video games or unlicensed Advanced Dungeons & Dragons 2nd Edition manuals.

The second edition of the Advanced Dungeons & Dragons game featured both a higher number of books of monsters^[4] - "many tied to their growing stable of campaign worlds"^[5]: 221 - and more extensive monster descriptions than both earlier^[1] and later editions, with usually one page in length.^{[6][7][8][9][10]: 106–107} Next to a description, monster entries in this edition contained standardized sections covering combat, their habit and society, and their role in the eco-system.^[6][7][11] While later editions gave the various creatures all the attributes which player characters had,^[9][12] 2nd edition only listed intelligence^[6][7] as a characteristic important for creating challenging encounters in the game.^[13]

The 2nd edition also used a unique format in the form of Monstrous Compendiums of loose sheets that could be collected in a folder, and allowed the combination of monster books together with individual monster pages from boxed sets.^{[6][10]: 106–107 [1]} This "unruly" format was abandoned again in 1993 in favor of bound books.^{[5]: 247 [7][14]: 83} In parallel with this change, the 2nd edition introduced colored images for each monster, which became standard in later editions of the game.^{[15]: 24 [7][9][16]} Referencing Wizards of the Coast art director Dawn Murin, GameSpy author Allan Rausch found that until the 2nd edition the artwork depicting monsters was influenced by the popular culture of the late 1970s. As a result, creatures that were fearsome by description were not taken seriously due to ill-suited visuals. Likewise, humanoid monsters too closely resembled humans to be compelling. In the view of Rausch as well as Backstab reviewer Michaël Croitoriu, the Planescape setting marked a turning point for these shortcomings, which also had a significant impact on the presentation of the 3rd edition.^[17][18]

The second edition's monsters were based on original inventions, fantasy literature, and mythologies from various cultures.^{[1][14]: 27, 29} Many monsters were updated from earlier editions, but the 2nd edition also introduced a great number of new creatures.^[7][8]

Some types, such as devils and demons, were initially removed by TSR in response to a moral panic promoted by Patricia Pulling's advocacy group Bothered About Dungeons and Dragons (BADD).^{[19]: 129–130 [20][5]: 223} These were later reintroduced, sometimes with different names to avoid complaints.^{[14]: 83–84 [21]}