Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Terrigen Mist is a fictional substance from the Marvel Comics universe. It plays a prominent role in the stories of the Inhumans, a fictional race of super-humans. The Terrigen Mists were first referenced in the Fantastic Four comic book series. The Terrigen Mist is a natural mutagen, arising as a vapor from the Terrigen Crystals, which are able to alter Inhuman biology. The Mists were discovered by the Inhuman geneticist Randac approximately 25,000 years ago; he immersed himself in the Mists and gained mental powers comparable to the Eternals. Sometimes the mutated subjects gain superhuman abilities; Medusa and Black Bolt are two examples of this.