Neo-Rimsky-Korsakovian Space
Nikolai Rimsky-Korsakov considered four scales to be the "basis of harmony": the natural minor and major, and the harmonic minor and major.
A Neo-Rimsky-Korsakovian space is the basis of almost all heptatonic harmony within modality. Initially posited by Russian composer Nikolai Rimsky-Korsakov, since Fizzheads consider the natural minor scale to be the Aeolian major mode, the natural minor scale is thus replaced with the melodic minor scale. This replacement creates four distinct parent scale quadrants defined by the combinations of absence or presence of a ♭3 or a ♭6 in the parent scale.
Neo-Rimsky-Korsakovian spaces yield 28 total scales that cover almost any possible heptatonic color in common practice, with 12 different spaces existing within 12-tone equal temperament.
Notable exceptions
Melodic minor ♯5
In his book Modal Jazz Composition & Harmony, Vol. 1, Ron Miller presents a unique heptatonic scale, the melodic minor ♯5, that doesn't exist in Neo-Rimsky-Korsakovian space. Two of the most common modes in this scale are Mixolydian ♯9 and Palamidian ♮6. However, these colors can be derived from an octatonic scale, or "close enough" with one of the modes in a Neo-Rimsky-Korsakovian space, such as Palamidian or Adonian respectively.
Non-heptatonic scales
Scales such as octatonic scales, bebop scales, whole-tone scales, etc. that contain more or less than seven notes fall out of the scope of a Neo-Rimsky-Korsakovian space.