The Mr. Saturn (どせいさん Dosei-san) are a species in EarthBound and Mother 3 and serve as the unofficial mascot for the trilogy. They are strange, possibly extra-terrestrial life forms who reside in both Eagleland's Saturn Valley and the Nowhere Islands's Saturn Valley in EarthBound and Mother 3, respectively. They are characterized by huge noses, four whiskers, and a single hair with a small red bow. They are generally very peaceful and generous, offering free coffee and stays at the hotel. They speak Saturnian (composed of odd looking English letters), and in the English translation erratically use the words "boing," "ding," and "zoom" at the ends of their sentences. The Japanese font is said to be inspired by the handwriting of the young daughter of EarthBound's designer, Shigesato Itoi.

Of Mr. Saturn, Itoi has stated that the race is the symbol of innocence in EarthBound. The Mr. Saturns are often said to have no gender, although a Mr. Saturn in Mother 3 exclaims that they are a girl.

Their village has round homes which resemble flying saucers and strange furniture, such as Automatic Teller Machines which bounce up and down in place and resemble Mr. Saturn. Some of the Mr. Saturns' preferred foods are "peanut cheese bars" and "piggy jelly", goods that can be purchased in the Saturn Valley shop. Their coffee apparently has psychoactive properties other than caffeination, since both Ness and Lucas each receive a message set to a surreal and psychedelic background upon drinking some Saturnian coffee.