Null is an English word meaning 'nothing' or without value or consequence. It is derived from the Latin word nullus meaning 'none'.
Null may refer to:
- Null (computer programming), a special value in computer programming
- Null, in law, having no legal validity. See Void (law)
- Null (mathematics), a zero value in several branches of mathematics
- /dev/null, the null device in Unix-like operating systems, equivalent to the NUL device on CP/M, DOS, and Windows operating systems
- Null (physics), a concept in electromagnetism and theoretical physics
- Null (SQL), a special marker and keyword in SQL
- Null allele (genetics), also see amorph
- Null character, an ASCII value of 00 commonly used as a terminator, separator or filler
- Null cipher, a ciphertext symbol
- Null hypothesis, a hypothesis in statistics
- Null morpheme, a concept in linguistics
- Null result, the absence of the expected result in a scientific experiment
- KK Null, a Japanese musician
- The Null Corporation, is the current imprint for Nine Inch Nails.