Dark matter was a type of matter which was thought to make up the majority of the universe's mass.

Dark matter was normally harmless, but in 2356, the Romulan Star Empire, with the aid of a Shepherd, developed a cloaking device which produced a mutated strain of dark matter that caused madness and death. (VOY novel: Cloak and Dagger)

In 2380, the USS Titan discovered a type of dark matter formation called exotic matter plasmids in the Occultus Ora region of the Gum Nebula. (TTN novel: Sword of Damocles)

The Totality was a dark matter-based lifeform which invaded the Milky Way Galaxy in the early 2380s. (TOS novels: Captain's Blood, Captain's Peril, Captain's Glory)


States of matter: solidliquidgasplasma
Types of matter: antimatterdark matterprotomatter