The Hitchhiker's Guide to the Galaxy is a comedy science fiction series created by Douglas Adams. Starting out as a radio comedy broadcast on BBC Radio 4 in 1978, it was later adapted to other formats, including stage shows, 5 novels, comic books, a 1981 TV series, a 1984 video game, and 2005 feature film.

In 2017, BBC Radio 4 announced a 40th-anniversary celebration with Dirk Maggs, one of the original producers, in charge. This sixth series of the radio comedy is based on Eoin Colfer's book And Another Thing, and includes additional unpublished material by Douglas Adams. It began its broadcast in March 2018.

The narrative across the six parts follows the misadventures of the last surviving man, Arthur Dent, following the demolition of the planet Earth by a Vogon constructor fleet to make way for a hyperspace bypass. Dent is rescued from Earth's destruction by Ford Prefect, a human-like alien writer for the eccentric, electronic travel guide The Hitchhiker's Guide to the Galaxy, by hitchhiking onto a passing Vogon spacecraft. Following his rescue, Dent explores the galaxy with Prefect and encounters Trillian, another human that had been taken from Earth prior to its destruction by the President of the Galaxy, the two-headed Zaphod Beeblebrox, and the depressed Marvin, the Paranoid Android. Certain narrative details were changed between the various adaptations.

Presented here are all six radio series as follows:

1 The Hitchhiker's Guide to the Galaxy2 The Restaurant at the End of the Universe3 Life, the Universe and Everything4 So Long, and Thanks for All the Fish5 Mostly Harmless6 And Another Thing...