Team Fortress', one of the most popular mods ever, was originally a 'Quake' total conversion.

Beholders also make an appearance in a very popular mod for The Elder Scrolls: Oblivion.

Some popular mods extensively change the game, adding historical flavor, fantasy scenarios, or new game mechanics.

Some popular and recent mods are:

Many popular mods are quite often crowdsourced, if for nothing other than QA.

Team Fortress Classic was an extremely popular mod for Half-Life created in April 1999.

A healthy mod community greatly increase a game's longevity and the most popular mods have driven purchases of their parent game to record heights.

Given the core gamer demographic, modifications that make female characters appear nude or topless are among the most popular mods.

This allows for the kind of success seen by popular mods such as the Half-Life mod Counter-Strike.

The most popular mods packages are: