Hexen II is a 1997 first-person shooter game developed by Raven Software and published by id Software for Windows. It is the third game in the Hexen/Heretic series, and the last in the Serpent Riders trilogy. Using a modified Quake engine, it features single-player and multiplayer game modes, as well as four character classes to choose from, each with different abilities. These include the "offensive" Paladin, the "defensive" Crusader, the spell-casting Necromancer, and the stealthy Assassin.

Improvements from Hexen: Beyond Heretic and Quake include destructible environments, mounted weapons, and unique level up abilities. Like its predecessor, Hexen II also uses a hub system. These hubs are a number of interconnected levels; changes made in one level have effects in another. Furthermore, the Tome of Power artifact makes a return from Heretic.

The gameplay of Hexen II is very similar to that of the original Hexen. Instead of three classes, Hexen II features four: Paladin, Crusader, Assassin, and Necromancer, each with their own unique weapons and play style.

Hexen II also adds certain role-playing video game elements to the mix. Each character has a series of statistics which increase as they gain experience. This then causes the player character to grow in power as his or her HP and mana increases.

Thyrion is a world that was enslaved by the Serpent Riders. The two previous games in the series documented the liberation of two other worlds, along with the death of their Serpent Rider overlords. Now, the oldest and most powerful of the three Serpent Rider brothers, Eidolon, must be defeated to free Thyrion. Eidolon is supported by his four generals, themselves a reference to the Four Horsemen of the Apocalypse. To confront each general, the player has to travel to four different continents, each possessing a distinct theme (Medieval European for Blackmarsh, Mesoamerican for Mazaera, Ancient Egyptian for Thysis, and Greco-Roman for Septimus). Then, finally, the player returns to Blackmarsh in order to confront Eidolon himself inside of his own dominion Cathedral.

What was originally supposed to be the final game in a trilogy, the sequel to Hexen was originally titled Hecatomb but was abandoned after John Romero left id Software in 1996. Activision, the distributor at the time, pressured Raven Software to split development of Hecatomb into two different games, Hexen II and Heretic II. Activision felt that the previous entries in the series, Heretic and Hexen, were different enough from one another that they should treat them as separate entities going forward, instead of just one final game to complete a trilogy. Only a select few ideas of Romero's from Hecatomb would ultimately make their way into what became Hexen II and Heretic II.

Hexen II was based on an enhanced version of the Quake engine. Hexen II, by way of the Quake engine, uses OpenGL for 3D acceleration. However, due to the prevalence of 3dfx hardware at the time of release, the Windows version of the game installs an OpenGL ICD (opengl32.dll) designed specifically for 3dfx's hardware. This driver acts as a wrapper for the proprietary Glide API, and thus is only compatible with 3dfx hardware. Custom OpenGL drivers were also released by PowerVR and Rendition for running Hexen II with their respective (and also now defunct) products. Removal of the ICD allows the game to use the default OpenGL system library. Much of the music in this game is remixed versions of the soundtracks of Hexen and Heretic to match the hub themes.

Activision acquired the rights to publish versions of the game for the PlayStation and Sega Saturn. Neither port was released.