HDD may refer to:
- H. D. Deve Gowda, former Prime Minister of India
- Hard disk drive
- Hand Drawn Dracula, a record label
- Head-down display
- Heating degree day
- High definition display
- Honorary Doctor of Divinity
- Horizontal Directional Drilling
- Hyderabad Airport (Sindh) (IATA:HDD), in Pakistan
- Template:Mono; see Device file § naming conventions
- Hard Drive Divinity, the transformed state of CPUs in Hyperdimension Neptunia
- Handan East railway station, China Railway pinyin code HDD