Along with speaking English, most intelligent aliens look a remarkable amount like humans. It is amazing that creatures developed so similarly, even though we lived in different planets and different galaxies. Even the Breen, a species in Star Trek whose bodies are never seen except completely encased in suits, are bipedal. The Breen are mysterious, with only guesses regarding why they were the suits and what they look like underneath. They seem so foreign, yet at the same time, so similar in their two-legged-ness. Not only are they bipedal, but like humans, they also have two arms and one head. I know that the Alien Actors Guild (AAG!) only allows bipedal aliens to join, making it extremely difficult for film or television to employ non-bipedal creatures. However, producers could make more effort towards equal representation of the non-bipedal variety.
Most of the time, creatures with more or less than two legs have only served as peripheral characters in film and television, barely seen at all. When they are present, they are often evil villains, like Jabba the Hut in Star Wars. Jabba was very resistant to taking the role at all, but claimed that even a negative presence in the media was better than no visibility for his species. Jabba has not only had to overcome earthlings’ bias towards the non-legged, but also bias towards his glandular disorder and weight issues.
Farscape does the best job so far on Earth at including aliens with multiple extremities in major and positive roles. Pilot is one of the few non-bipedal aliens to serve as a main character. Moya, the spaceship, is also without legs, although with great propulsion, and is a major element in the show. Indeed, the series could not exist without some form of Moya. I hope she asked for a raise. Although Rygel XVI isn’t exactly without two legs, the fact that the deposed Hynerian leader flies around on his Thronesled most of the time, rarely walking or showing his legs, makes him appear non-bipedal at times.
Shows are making progress towards the inclusion of more or less legs. However, it will be a long time before the leggy or leggless creatures feel accepted in the hearts of earthlings.