Enormous creatures Miyazaki created by combining insects and arthropods, which exist in a perpetual larval form until their lives end. They were created specifically to represent a new ecosystem for the story, simultaneously stimulating a sense of wonder and alienation. He chose their form in an effort to defy easy identification with existing life forms, to make it more difficult to discern their thoughts from their appearance and to resist empathy.

The Ohmu play a very important role in the story of Nausicaä. The Ohmu are greatly feared by many people in Nausicaä's world: though they are ordinarily docile, killing any insect while in the forest will drive any nearby Ohmu into a berserk rage, signified by their eyes changing to bright red as opposed to blue when they are calm. Due to their great size, they can destroy entire settlements in this state and the spores from forest plants which they scatter as they move can kill crops and render an area unsuitable for human life if left unchecked. However, the molted exoskeletons of the creatures are stronger than ceramics, capable of resisting most human weaponry and thus highly sought-after as material for weapons, tools, as well as structures. The Ohmu possess a hive mind with which certain sensitive people may communicate. They also appear to have empathic powers as well: able to discern emotions through their tentacle feelers as they have done with Nausicaä herself. While most of the giant insects in the Sea of Corruption are driven by basic instinct, the Ohmu exhibit a greater level of intelligence.

Pronunciation: Ohm: /oʊm/. The Japanese name, (王蟲 (Ō mu(shi))), consists of the kanji for king and insect or bug. Transliterated as Ohmu in manga translations and as Ohm in the film's subtitles. The name has its origins in a mixture of the words for the king's worm, the sandworm from Dune, and Daijiro Morohoshi's Buddhist term ohm.

The creatures were renamed Gorgons for the Warriors of the Wind version of the film.