I'm Pink, therefore im Spam

 

Its a strange thing about aliens, by they're essential nature, they must be different, A lot of common sci-fi aliens are humanoid, Star Trek Next Gen was especially guilty of this as almost every alien race was fundamentally humanoid, but with something wrong with their nose. Farscape and Babylon 5 went a bit further, using some nice alien physiology and adding extra limbs etc. But as Arthur C Clarke pointed out that eventually technology will advance to the point where it will  be indistinguishable from magic, alien intelligence would be so radically different as to be incomprehensible to us. The motivations of an alien being might be impossible for us to understand, let alone the language. Sci Fi often bridges the communication gap by wheeling in the 'psychic' connection or the telepathy card, thereby obviating the necessity for doing the donkeywork of practically communicating and examining the alien perception. Gigers Alien for example, whilst being physically unique, is purely inimical in intent while displaying a base animal intelligence. In the Andromeda Strain, the alien lifeform was almost microscopic and crystalline in form, but did not display any sign of intelligence that we might recognise.  Star Wars uses a galaxy of alien forms, but again the majority of these are humanoid. Ron Cobb, production designer on the first film suggested an ambulatory plant as a cantina alien, but it never made it to the final cut. The TV series, the Outer Limits had a huge cast of aliens some of which such as the Chromite and the Glob really made good use of the alien form. Dr Who is a serial offender for humanoid aliens as most of the creatures are actors dressed in suits and makeup. The Daleks manage to break this trend, even though they look like robotic dustbins, they still manage to exude a cold alien intelligence and even after years of exposure, still manage to scare. The Quatermass Xperiment had an early example of a truly different alien, which by the end of the film had metamorphosed into a shapeless mass of life, which for 1957 even managed to suspend disbelief and look real.