Complexity is the property of a system to defy full description.
Complexity may also refer to:
Arts and entertainment
- Complexity Gaming, an American esports organization
- "Complexity", a song by Front Line Assembly from the 1997 re-release of the album The Initial Command
- "Complexity", a song by Eagles of Death Metal from the 2015 album Zipper Down
- "Complexities", a song by Daniel Caesar from the 2019 album Case Study 01
Mathematics and science
- Complexity (journal)
- Computational complexity, of algorithms
- Game complexity, in combinatorial game theory
- Integer complexity, in number theory
- Language complexity, a linguistic hypothesis