# D (disambiguation)

D is the fourth letter of the Latin alphabet.

D or d may also refer to:

## Music

### Bands and musicians

• D (band), a Japanese rock/metal band
• "The D", one of the names of comedy rock band Tenacious D
• "d:" or "d:?", often used to refer to the Christian rock band Delirious?
• "D!" or "Dee!", names of Detlef Soost, a German dancer and choreographer
• D, the bass player for Australian band Testeagles

## Entertainment and film

• D (film), a 2005 Bollywood film
• D Magazine, a magazine for the city of Dallas, Texas, US
• D, a weekly supplement to the Italian newspaper la Repubblica
• D (series), a video game series
• D (video game), a game released in 1995 for the PC, 3DO, PlayStation and Sega Saturn
• Count D, a character in the anime/manga series Pet Shop of Horrors
• D is the character in a series of novels titled Vampire Hunter D by Hideyuki Kikuchi
• D is a nickname given to Count Dracula in the novel Dracula written by Bram Stoker
• D, one of the characters in Another Code: Two Memories (Trace Memory)
• Initial D, a 1995 Japanese manga and anime about mountain drifting that has spawned several arcade and console games
• Substance D, a fictional recreational drug in the novel and film A Scanner Darkly

## Science

• D region, part of the ionosphere in earth science
• Deci- (d), the SI prefix meaning one tenth
• Day (d), in metrology

### Mathematics

• d, the symbol for the total differential operator; in a related but more general meaning, it is the exterior derivative operator in differential geometry
• Thirteen (D in hexadecimal and other positional numeral systems with a radix of 14 or greater)
• Blackboard bold ${\displaystyle \mathbb {D} }$, representing the unit disk in the complex plane, or the decimal fractions; See Number
• d, often a variable for the diameter of a circle in geometry
• D and d, the derivative operators
• Five hundred, (D in Roman numerals)
• Divisor function (d(n)), the number of positive divisors of an integer n

## Technology and engineering

### Computing

• D - Minimal Protection, a security division in the Trusted Computer System Evaluation Criteria
• -d, a suffix of a daemon, a computer program that runs as a background process
• .d, a pathname component suffix for a directory; for example with the init program
• .d, a file format used for Agilent MassHunter mass spectrometry software