H.R. Giger's recent passing has brought to light some new accounts of the film production for which he was best known, Ridley Scott's Alien. The Strange Shapes fan blog recounts the little known story about how the original headpiece for the eponymous creature was created for infamous reveal shot. Apparently, two effects teams were hired to design a mechanized head for the scene--one at Shepperton studios which had previously build the R2-D2 droids for Star Wars, and a second led by Italian effects master Carlo Rambaldi, who was then best known for designing E.T. for Spielberg. (This is the same Rambaldi who took the E.T. design job away from Rick Baker.)
As the story goes, both teams failed to please Giger (who was famous for being difficult to collaborate with) and rushed to build their animating Xenomorph heads by the shoot date in Fall of 1978. Rambali's team won out with a complex skull made of fiberglass, metal tracks, and puppeteering cables, while the Shepperton team was given the task of mechanizing the creature's tail (which was eventually just puppeteered with external wires). There was a lot of politicking on-set between the teams, it's the kind of tension and drama that happens on every film production that behind-the-scenes fans love to hear.
Scott wound up not using most of Rambaldi's mechanisms, opting for an extended close-up of the Xenomorph for its glamour shot. But the Alien franchise would continue to have a close relationship with practical effects artists--Stan Winston's studio created the animatronics for the sequel, and released its own effects test videos not too long ago (embedded below).