Many merchandising and spin-off items (or "Hitch-Hikeriana") were produced in the early 1980s, including towels in different colours, all bearing the Guide entry for towels. Later runs of towels include those made for promotions by Pan Books, Touchstone Pictures / Disney for the 2005 movie, and different towels made for ZZ9 Plural Z Alpha, the official Hitchhiker's Appreciation society. Other items that first appeared in the mid-1980s were T-shirts, including those made for Infocom (such as one bearing the legend "I got the Babel Fish" for successfully completing one of that game's most difficult puzzles), and a Disaster Area tour T-shirt. Other official items have included "Beeblebears" (teddy bears with an extra head and arm, named after Hitchhiker's character Zaphod Beeblebrox, sold by the official Appreciation Society), an assortment of pin-on buttons and a number of novelty singles. Many of the above items are displayed throughout the 2004 "25th Anniversary Illustrated Edition" of the novel, which used items from the personal collections of fans of the series.
Stephen Moore recorded two novelty singles in character as Marvin, the Paranoid Android: "Marvin"/"Metal Man" and "Reasons To Be Miserable"/"Marvin I Love You". The last song has appeared on a Dr. Demento compilation. Another single featured the re-recorded "Journey of the Sorcerer" (arranged by Tim Souster) backed with "Reg Nullify In Concert" by Reg Nullify, and "Only the End of the World Again" by Disaster Area (including Douglas Adams on bass guitar) listen . These discs have since become collector's items.
The 2005 movie also added quite a few collectibles, mostly through the National Entertainment Collectibles Association. These included three prop replicas of objects seen on the Vogon ship and homeworld (a mug, a pen and a stapler), sets of "action figures" with a height of either 3 or 6 inches (76 or 150 mm), a gun—based on a prop used by Marvin, the Paranoid Android, that shoots foam darts—a crystal cube, shot glasses, a ten-inch (254 mm) high version of Marvin with eyes that light up green, and "yarn doll" versions of Arthur Dent, Ford Prefect, Trillian, Marvin and Zaphod Beeblebrox. Also, various audio tracks were released to coincide with the movie, notably re-recordings of "Marvin" and "Reasons To Be Miserable", sung by Stephen Fry, along with some of the "Guide Entries", newly written material read in-character by Fry.