DET or Det may refer to:
- Detroit (Amtrak station); Amtrak station code DET
- Coleman A. Young International Airport, formerly Detroit City Airport, IATA Code DET
- Diethyltryptamine, a psychedelic drug
- Detection error tradeoff
- It (Christensen book), a book of poetry by Inger Christensen, with the original title Det
- The mathematical determinant
- Department of Education and Communities (New South Wales), formerly the Department of Education and Training (DET)
- 14 Intelligence Company, an alleged covert intelligence unit of the British Army in Northern Ireland, known as "The Det"
- Detective (abbreviation)