Storobia Archive
Marvin has been in the story since the early days, first appearing in the original radio series. He is one of the most memorable and popular characters.
Little physical description is given of Marvin, so the TV series and the film have totally different interpretations - in the 2005 film he has a bobble head, presumably because he has "a brain the size of a planet".
The word "paranoid" seems strange for Marvin, he is more clearly depressed. In fact he's downright miserable. He was created by the Sirius Cybernetics Corporation ("go stick your head in a pig") and is a "personality prototype" ("you can tell can't you").
Marvin has reason to be depressed. Despite haven't a huge intellect (he worked out the square root of minus one - presumably using something more interesting than the standard system of imaginary numbers) he spends most of his time doing menial tasks. He once spent several million years in a car park. Parking cars, of course.
Marvin provided some of the greatest lines in HHG. One of his catchphrases is "I've got this terrible pain in all the diodes down my left side".
In the original radio series Marvin was voiced by Stephen Moore. In the 2005 movie the role was played by Warwick Davis and voiced by Alan Rickman.