All sensible people are selfish, and nature is tugging at every contract to make the terms of it fair.

Writer and Atheist                          

Selected Works:

Novels in the Hitchhiker Series:

The Hitchhiker's Guide to the Galaxy - 1979
The Restaurant at the End of the Universe - 1980
Life, the Universe and Everything - 1982
So Long, and Thanks For All the Fish - 1984
Mostly Harmless - 1992

The Dirk Gently Series:

Dirk Gently's Holistic Detective Agency - 1987
The Long Dark Tea-Time of the Soul - 1988
The Salmon of Doubt - incomplete, 2002

Novels:

The Meaning of Liff - 1983, with John Lloyd
The Hitchhiker's Guide to the Galaxy: The Original Radio Scripts - 1985, with Geoffrey Perkins
The Utterly Utterly Merry Comic Relief Christmas Book - 1986, edited by Douglas Adams and Peter Fincham, which includes
Young Zaphod Plays it Safe - also printed in a slightly reworked version in The Wizards of Odd, The Salmon of Doubt, and several omnibus editions of Hitchhiker

The Private Life of Genghis Khan, also available in the first edition of The Salmon of Doubt, though later removed due to copyright issues

A Christmas Fairly Story by Douglas Adams and Terry Jones
A Supplement to The Meaning of Liff with John Lloyd and Stephen Fry - 1987
The Deeper Meaning of Liff - 1990, with John Lloyd; extended version of The Meaning of Liff.
Last Chance to See - 1990, with Mark Carwardine, non-fictional account of several trips to see endangered species

The Illustrated Hitchhiker's Guide to the Galaxy - 1994
Douglas Adams's Starship Titanic - 1997, written by Terry Jones. Also available as an audiobook, read by Terry Jones.
The Salmon of Doubt - 2002, unfinished novel manuscript - 11 chapters, short stories, essays, and interviews, also available as an audiobook, read by Simon Jones

Other Works: 

Monty Python's Flying Circus Episode 45, Party Political Broadcast on Behalf of the Liberal Party - 1972
The Pirate Planet - a Doctor Who serial first broadcast in 1978, available on VHS and DVD
City of Death - a Doctor Who serial, co-written with Graham Williams, based on a story by David Fisher, first broadcast in October 1978, available on VHS and DVD.
Shada - a Doctor Who serial, originally intended to be broadcast in January/February 1980. Available footage released on video in 1992. A complete, animated form was made available on the web in 2003, and on CD later that same year.
The Hitchhiker's Guide to the Galaxy - computer game - 1984, with Steve Meretzky
Bureaucracy - computer game - 1987
Hyperland - TV documentary - 1990
Starship Titanic - computer game - 1998
h2g2 - internet project - 1999
The Internet: The Last Battleground of the 20th century - radio series - 2000
The Hitchhiker's Guide to the Future - radio series - 2001

In 2004, BBC Audio published a 3-CD set entitled Douglas Adams at the BBC, which covers the author's work from 1974 to 2003, including posthumous projects and tributes.                          

Mother Janet Donovan
Father Christopher Douglas Adams
Sister - Susan
Parents divorced in 1957.
Christopher Adams remarried in July 1960, to Judith Robertson. From this marriage, Douglas Adams had a half-sister, Heather. Janet remarried in 1964, to a veterinarian, Ron Thrift, providing two more half-siblings to Douglas; Jane and James Thrift.
Wife Jane Belson, one daughter Polly Jane Rocket Adams, born 1994.                          

Adams was a self-declared "radical atheist", he used the term for emphasis, so that he would not be asked if he in fact meant agnostic.