Smut may refer to:
- Smut (fungus), a group of plant parasitic fungi
- Smut (comics), an adult British comic title dating back to the 1980s
- A colloquial term for obscenity in general or pornography in particular
- Jimmy Means, a former NASCAR driver nicknamed "Smut"
- The song "Smut" by Tom Lehrer from the album That Was the Year That Was (referencing the colloquial meaning of the term)
- A nickname for the Scaled Composites ATTT aircraft