E-Space, short for Exo-Space, is an alternate continuum of reality, existing outside the normal universe (N-Space). Entrance can be gained to this reality through a CVE (Charged Vacuum Emboitement). Numerous worlds exist in E-Space, including the misty world of Alzarius and the bleak Vampire Planet. Between E-Space and N-Space exists a misty void, which contains the Warriors' Gate and can be accessed by the time-sensitive Tharils. The natives of Logopolis used E-Space to save the universe from heat death.
The Fourth Doctor, Romana, and K9 Mark II found themselves trapped in E-Space after encountering a CVE. While Romana and K9 stayed in the Warriors' Gate, the Doctor and his new companion Adric continued on back to N-Space.