Against the Giants is an adventure module written by Gary Gygax and published by TSR in 1981 for the Dungeons & Dragons fantasy role-playing game. It combines the G series of modules previously published in 1978: Steading of the Hill Giant Chief, Glacial Rift of the Frost Giant Jarl, and Hall of the Fire Giant King. All three were produced for use with the 1st edition Advanced Dungeons & Dragons rules. In 1999, to recognize the 25th anniversary of TSR, the company released an updated version, Against the Giants: The Liberation of Geoff. Later in 1999, Wizards of the Coast published a novelization of Against the Giants by Ru Emerson.

In the Dungeons & Dragons role-playing game, an adventure or module is a guide for managing player knowledge and activities within a specific scenario. Commercially, a published adventure comes as a pre-packaged book or box set that is used exclusively by the Dungeon Master. It typically contains background information for the plot or story, maps, vignettes of interesting locations, site inventories, creature descriptions and statistics, player visual aids, and suggested rules for evaluating events and likely player actions.