- "…those of us assigned to the base heard rumors that it doesn't operate in what we'd call normal hyperspace. It fires through a hole in the continuum that it makes itself. Everybody was calling it 'sub'-hyperspace."
- ―Finn, discussing Starkiller Base
Sub-hyperspace was the name given by members of the First Order to a hole in the realspace continuum through which phantom energy traveled. Unlike typical hyperspace, which moved across the galaxy, sub-hyperspace would move through the galaxy. The First Order's Starkiller Base was able to collect a form of dark energy called quintessence, transform it into phantom energy, and unleash it along a linear path through sub-hyperspace, enabling it to destroy entire star systems across vast interstellar distances in real-time. The Hosnian Cataclysm in 34 ABY revealed a strange side-effect of sub-hyperspace: the vast quantities of energy released by firing of the Starkiller Base had the ability to create a temporary rip in sub-hyperspace, allowing the Hosnian system's destruction to be viewed from across the galaxy as it happened. 
- Star Wars: The Force Awakens novelization (First appearance)