The Alien concept art designed by artist H.R. Giger helped transform the project from a b-movie into a genre classic. Given the lifecycle of the xenomorph itself, its somewhat fitting Alien also had a difficult birth. The idea was first conceived by writer Dan O'Bannon, who collaborated with director John Carpenter (Halloween) on a low-budget sci-fi comedy called Dark Star in 1974. The movie followed the aimless misadventures of a crew of astronauts, with one sequence finding Pinback - also played by O'Bannon - chasing a small alien creature through the ship's vents.
This gave O'Bannon the idea of writing a scary movie based around the concept. During this period he also collaborated on director Alejandro Jodorowsky's famously unproduced version of the novel Dune, where he came across the work of Swiss artist H.R. Giger. Giger's concept art for Dune, which depicted his trademark biomechanical style, made a huge impression on O'Bannon. When that version of Dune collapsed O'Bannon concentrated on writing Alien with collaborator Ron Shusett instead.
The original version of the script was dubbed Star Beast, which was later changed to Alien based on the number of times the word appeared in the script. O'Bannon and Shusett had a hard time thinking of a unique way for the creature to get onboard the spaceship until the latter conceived of a parasite implanting an embryo into a crew member, which later eats its way out. The duo had trouble selling their script, with veteran low-budget producer Roger Corman (Death Race) the only one willing to make it, until the original Star Wars became a big hit in 1977. This led to a studio frenzy to greenlight any space scripts they had.
Alien producers Walter Hill (48 Hours) and David Giler rewrote the script and introduced Ripley, who was originally written as a male character. Without a doubt, the biggest design issue facing the project was the title monster itself. A number of artists took a stab at conceiving of the monster, but it wasn't until O'Bannon introduced director Ridley Scott (Blade Runner) to Giger's work that it all clicked. Scott fell in love with the artist's unique, nightmarish style, and felt his painting Necronom IV represented what the creature should look like.
Giger was thus hired as a designer, with his Alien concept art defining the lifecycle of the monster and the derelict craft. Giger's beautifully designed monster suit still looked like a man in a rubber costume, but Scott decided to only show the creature in pieces so the audience's imagination could fill in the gaps, making it even more terrifying. Giger's Alien concept art is also responsible for the dead Space Jockey - a creature whose origins would be explored further in Scott's 2012 Alien prequel Prometheus.
H.R. Giger's Alien concept art helped transform the movie from something the studio considered a b-level monster flick to a classy, landmark sci-movie. Of course, the combination of script, direction, and casting played an important role too, but if it wasn't for the Swiss artist's singular Alien concept art the movie may never have captured audiences imagination the way it did. In fact, it's doubtful the Alien franchise itself would have blossomed without his one of a kind version.