You know the one who looks like this 
and graces the cover of the novel. I’ve only read the first book and I don’t recall any mention of who or what he is. Google wasn’t much help either. So, who is he, who thought him up, and why?
He’s called the “Cosmic Cutie” (if you do a google search, include the word “hitchhiker” if you want to find anything.) and was created for the American market paperback books. Douglas Adams absolutely hated it.
He’s just zis guy, you know?
Neat. Can anyone elaborate on this? maybe a link?
Being someone who got to know the series through the American market paperbacks, the Cosmic Cutie (I never knew he had a name until now) has always been a defining Hitchhiker’s Guide image for me. It fascinates me to learn that an image that has always so immediately connected me to the series had been hated by the author (fascinated but not surprised, I know it’s not uncommon for authors to hate what marketing attaches to their work).
The first time I saw anything related to Hitchhiker’s Guide, the album cover and books had abstract imagery, the most vivid being a rubber duck. This was the Golgafrincham ‘B’ Ark Captain’s rubber duck, it turns out, but that wasn’t easy to determine.
My copy of “Life, the Universe, and Everything” has a soda can ring pull on it, for no demonstratively logical reason. My guess is that logic wasn’t really considered a necessary element in their design decisionmaking.
For a moment, I thought the OP referred to Wowbagger the Infinitely Prolonged.
At first glance, I thought that the movie logo was a bird- the one from Mostly Harmless.