(Inside the the alien 'derelict' or 'Juggernaut' spacecraft, the search team find the latterly named 'Space jockey'.)
'They walked on and made another find' (Dallas looks upon the skeletal alien remains of what would latterly be nicknamed the 'Space Jockey') "Must've been a crew member... or a Hell's Angel biker."
2. 'Then Kane discovered a shaft--' Someone says to him, "Hey, careful. You don't know what's at the bottom, or how far down it is!" Kane ignores them, "I wonder what created it. An explosion -- a shaped charge!" he muses. "Naw, the sides are too smooth and regular." replies a team member. (Kane peers into the shaft, shining a beam down through its depths)
Hell's Space Jockey! 
Ooh - nice! I think we might be discovering a few things about this fellow in Ridley Scott's new Prometheus film this summer. But apparently, when I drew this (not bad eh?) I was still using the photos from the novel and CRACKED magazine as a reference. I'm guessing the "Hell's Angel Biker" quip came from the latter.
From CRACKED magazine - 1979 (see entire page)
I don't know if you've had a look at my earliest attempt at comically adapting ALIEN? Here's a detail with our friend Mr.Space Jockey/Navigator
This was done purely from memory after seeing my uncle's Giger Film Design book. Later, the trunk was added in blue biro - probably after I bought the novel.
I must have loved this!
It's a pity I did most of this comic on ruled foolscap paper, eh?
Check out the Star Wars age 9 way...
Ooh! I was enjoying a newly discovered technique in panel 2. See the green marker around that light stick thingy? I found that I could lay a ruler down and do quick staccato pen strokes against its edge - lift the ruler et voila! A very straight, sort of light-beam effect! See more SpFX over at Star Wars age 9! »
You know, the Alien pilot - or whatever he is - is never mentioned in the novel! Nothing about his ribs being bent outwards and all the rest of that good stuff!
It seems that the pilot as Giger refers to him, was one of the first satisfying experiences of his stint on the film. He seems to have been very frustrated and occasionally angered on seeing his designs compromised and even discarded for cheaper options such as re-using the underside of the derelict's exterior for an internal corridor. The 20th Century Fox execs amongst others, were constantly fretting over the budget and deadlines - despite their huge and unexpected success with Star Wars; and people like Dan O'Bannon - would fly over to the studios and start objecting to designs. Giger said: "I suppose I'm not (...) enough of a strategist to play the 'game'. Scott's tactics are quite different:
"Interesting', he (Scott) says, and I know at once that what he really means is 'Shit'."
"After this senseless bickering I urgently need fresh air." He seems to have greatly respected director Scott, who was on Giger's side creatively.
In any case, the pilot was executed to the designs. It's such an unlikely creature. "Biomechanical", it's seems to merge with the chair and the machinery. Putting a painting into 3d form would seem to raise all sorts of questions. How could people believe that a creature could function like that?
Still, if all of Giger's designs had been used, imagine what a jaw-dropper it would have been!