Parallel universe, alternate reality, etc. may refer to:

• Parallel universe (fiction), alternate universes, worlds, realities and dimensions in fiction
• Multiverse (science), the hypothetical set of multiple possible universes
• Many-worlds interpretation, of quantum physics

Parallel universe may also refer to:

• Parallel Universe (album), by "4 Hero"
• "Parallel Universe" (Red Hot Chili Peppers song)

Alternate reality may also refer to:

• Alternate Realities (Cherryh), an anthology of science fiction by C. J. Cherryh.
• Alternate Reality (computer game)
• Alternate reality game, a type of cross-media game.