One of the signature features of the titular creature(s) from the Alien franchise, besides their elongated heads, sharp teeth and lethally telescoping tongues, are their ability to grow quickly into a menace for those unfortunates that come across them. The design of these dangerous beings morphed in a similar manner.
You can trace the origin of the alien back to the 1974 sci-fi comedy Dark Star, co-written by eventual Alien co-writer Dan O’Bannon and eventual horror maestro John Carpenter. Produced on a shoestring budget of just $60,000, the movie features O’Bannon’s character Sgt. Pinback chasing an escaped alien creature around the ship. A decidedly low-tech alien.
O’Bannon would decide to take this aspect of the humorous Dark Star and give it the serious treatment in his next script, originally titled Star Beast. Later given the more mysterious name Alien, the image of the creature drawn by O’Bannon to illustrate the title character in his screenplay was little more than an amorphous blob, as seen in its expusion from the shuttle near the end of the script.
To further develop the alien’s appearance, O’Bannon requested the input of Ron Cobb, who had created the plethora of strange beings that populated the Mos Eisley Cantina in Star Wars. The multi-legged, hooks-for-claws monstrosity looked like this:
And, as we all know, ultimately H.R. Giger would design the alien used in the film, the construction of which included actual animal bones and a real human skull for the face. Effects guru Carlo Rambaldi created the mechanics for the articulated head. Here Giger is working on the suit, which would be worn in front of the camera by 6′ 10″ Nigerian art student Bolaji Badejo, below:
To keep suspension of disbelief high, Ridley Scott would only show brief glimpses of the alien, and keep it mostly shrouded in darkness. Still, the freakish appearance of the creature would leave a lasting impression on audiences, as well as the film landscape as a whole.