Background characters are, as the name implies, characters that appear in the background of some stages, they will appear in a stage that correspond to their home universe (i.e Shy Guys appear in Yoshi's Island). Note that background characters shouldn't be confused with stage hazards.
In Super Smash Bros.
Dream Land
- King Dedede appears floating in the background.
Saffron City
- A Pidgey appears flying in the background.
Yoshi's Island
- Shy Guys appears in the background.
- A Goonie, in it's Yoshi's Story design, occasionally flies in the background.
Congo Jungle
- Necky appears flying in the background.
In Super Smash Bros. Melee
Brinstar
- A statue of the chozo appear in the background.
Brinstar Depths
- Kraid appears in the background of the stage.
Fourside
- A U.F.O appears in the background and can be boarded.
Yoshi's Story
Jungle Japes
- Cranky Kong is seen walking back and forth in his cottage and rocking in his chair at various times.
In Super Smash Bros. Brawl
New Pork City
- A statue of Pokey Minch from Earthbound appears in the right side of the stage.
Lylat Cruise
- Multiple ships appear battling in the background.
Smashville
- Villagers from Animal Crossing appear in the background.
Yoshi's Island
- For a third time, Shy Guys appear in the background.
Frigate Orpheon
- The Parasite Queen, Metroid Prime's first boss, appears in the background in Frigate Orpheon.
Pokémon Stadium 2
- Electivire, Drifloon, Hoppip, Skarmory, Cubone and Dugtrio all appear in the background of the various elemental transformations of the stage.