^{This page is about the franchise as a whole. For the in-universe book, see The Guide. For individual iterations of the franchise with the same title, see installments below.}

The Hitchhiker's Guide to the Galaxy is a multimedia franchise created by Douglas Adams. It originated as a radio series first broadcast on BBC Radio in 1978. It went on to be adapted into several formats, each with interlinked but independent continuities.

1. Primary Phase [1978]
2. Secondary Phase [1978,1980]
3. Tertiary Phase [2004]
4. Quandary Phase [2005]
5. Quintessential Phase [2005]
6. Hexagonal Phase [2018]

1. The Hitchhiker's Guide to the Galaxy [1979]
2. The Restaurant at the End of the Universe [1980]
3. Life, the Universe, and Everything [1982]
4. So Long and Thanks for All the Fish [1984]
5. Mostly Harmless [1991]

A sixth book, And Another Thing... was written by Eoin Colfer and published in 2009 on the 30th anniversary of the original novel.

• The Hitchhiker's Guide to the Galaxy (1981) - BBC Television Series
• ABC Television Series - Unreleased [1980's]
• Hulu Series - Unreleased [in production hell]

• The Hitchhiker's Guide to the Galaxy (2005)
• Ivan Reitman Film Treatment - Unproduced film script [1987]

• The Hitchhiker's Guide to the Galaxy (infocom) [1984]
• Starship Titanic
• Milliway's - Unreleased Infocom sequel
• PC Platformer - Unreleased [early 2000s]
• Film Tie-In Adventure Game | Vogon Planet Destructor

• The Hitchhiker's Guide to the Galaxy (comics) - DC Comics adaptation of the first 3 novels [1991-1993]
• Various Stage Shows
• Towels