Cosmo may refer to:
- Cosmopolitan (magazine) magazine
- Cosmopolitan (cocktail), an alcoholic drink made from vodka, cointreau or triple sec, lime juice, and cranberry juice
- Cosmo's Cosmic Adventure, a 1992 computer game series, or its titular character
- Cosmo Software, the name of a VRML-player.
- Mazda Cosmo, a sports car which is similar to the MG Midget or Lotus Elan
- COSMO Solvation Model, a popular solvation model in computational chemistry by Andreas Klamt .
- Cosmoline, a firearm preservative .
- COSMO-SkyMed, an Italian earth observation satellite launched in 2007
The following people:
- Cosimo de' Medici, a ruler of Florence
- Cosimo I de' Medici, Grand Duke of Tuscany
- Cosimo II de' Medici, Grand Duke of Tuscany
- Cosimo III de' Medici, Grand Duke of Tuscany
- Fran Cosmo, former lead singer of Boston (band)
- COSMO (band) , Band formed by Fran Cosmo
- Cosmo Wilson, a rock & roll lighting designer and director
- Sir Cosmo Duff Gordon, passenger on the RMS Titanic
- Cosmo Gordon, 3rd Duke of Gordon, Scottish nobleman
And the following fictional characters:
- Cosmo Brown, the character played by Donald O'Connor in Singin' in the Rain
- Cosmo Kramer, the character played by Michael Richards in the NBC television sitcom Seinfeld
- Cosmo Topper, the main character in Topper, an early 1950s sitcom about a staid banker and three ghosts
- Cosmo Yuuki, the red-haired, hot-blooded main character of the Japanese animation Space Runaway Ideon, the main pilot of the godlike titular mech
- Cosmo, the character played by Ben Kingsley in Sneakers
- Cosmo the Cougar, Brigham Young University's official mascot
- Cosmo is a character in the cartoon The Fairly OddParents
- Cosmo (Sonic the Hedgehog), a character in Sonic X.
