90 may refer to:
- 90 (number)
- one of the years 90 BC, AD 90, 1990, 2090, etc.
- 90 (album), an album by the electronic music group 808 State
- 90 (EP), an album by the band South Club
- Atomic number 90: thorium
- 90 Antiope, double asteroid in the outer asteroid belt
