Universe

A universe is a term first used by the Smash Bros. community, as well the Smash Flash community, to collectively refer to all the particular characters, stages, items and other properties appearing in the fighting games that are thematically featured in another game franchise.

Main universes
These are the major franchises that the Super Smash Flash games classify as major enough that they assign each franchise its own unique series symbol (in the case for Super Smash Flash 2 only) that appears with characters and stages belonging to that franchise. These franchises generally have characters, stages, items, and other properties that all appear in Smash Flash. games as part of their primary content. However, the minimum requirement for an icon is to contribute one stage or one character to the games.

Supporting universes
These are the various franchises that have not been recognized as primary universes by any Smash Flash game, and this is indicated by the fact these franchises do not carry their own universe symbols. As a general rule, such universes lack any playable characters or stages in the games, but if any of the following franchises contributes an item, Assist Trophy, music, or some other minor element. Like in the original Smash Bros. games, the universe is assigned the property and its respective franchise the Smash Bros. universe symbol.