Acheron is a river in the Epirus region of Greece, believed in ancient Greek mythology to branch into the underworld.

Acheron may also refer to:

• Acheron, Victoria, a town in Australia
• Acheron (Elis), a river in the Peloponnese, Greece
• Acheron Island, an island off Queensland, Australia
• Acheron River (Victoria), Australia
• Acheron River (Marlborough), New Zealand
• Acheron River (Canterbury), New Zealand

• Acheron (Dungeons & Dragons), an Outer Plane in Dungeons & Dragons cosmology
• Acheron Hades, a villain in Jasper Fforde's book The Eyre Affair
• A main character of the webcomic Inverloch
• A powerful ghost in DC Comics that temporarily joins the Shadowpact
• The Acheron, a fictional 19th-century French warship in the motion picture Master and Commander: The Far Side of the World
• Acheron (LV-426), the planet-like moon where the film Alien and its sequel are primarily set
• Acheron Parthenopaeus, a character in the Dark-Hunter series of romance books
• "Acheron: Part 1" and "Acheron: Part 2", a two-part episode from the television series The Walking Dead
• Acheron, a playable character in Honkai: Star Rail

• Acheron (band), a Florida death metal band
• HMS Acheron, the name of several ships of the Royal Navy
• Acheron-class torpedo boat, a torpedo boat of the New South Wales Naval Brigade
• French submarine Achéron (Q150), a French Navy submarine commissioned in 1932 and scuttled in 1942
• Acheron language, a language of Sudan
• The earlier name for Abramelin, a Melbourne death metal band
• "Acheron/Unearthing the Orb", a song by the Sword from the album Warp Riders