**0S** (zero S) or **0-S** may refer to:

- 0s, the period from January 1, 1 AD to December 31, 9 AD, almost synonymous with the 1st decade (1-10).
- The period from January 1, 1 AD to December 31, 99 AD, almost synonymous with the 1st century (1-100).
- The period from January 1, 1 AD to December 31, 999 AD, almost synonymous with the 1st millennium (1-1000).
- 0S, 0°S, or zero degrees south, coordinate for the equator
- Zero S, a model of electric motorcycle
- 0 set, or zero set, a concept in mathematics
- 0 sum, or zero-sum, a theory in games and economics
- 0 sharp, also zero sharp or 0#, a concept in set theory
- 0 section, or zero section, a type of section in a Vector bundle