I've only watched the movies, but the aliens are mostly just humans with minor differences.
Vulcans = humans with pointy ears
Klingons = humans with weird foreheads
Romulans = pretty much Vulcans with a V on their forehead
This is more of an observation than a complaint, but it's kind of a letdown compared to Star Wars with their hundreds of creative creatures. Was it like this in the shows too?
Trek has always been lazy when it comes to its alien designs. The old bumpy headed alien of the week is a long standing Trek joke.
shareThe old album liner for the soundtrack to 'Star Trek: The Motion Picture' had a plethora of actors posing in alien costumes which, at the time, I assumed were in the movie. If you want to see some of the most lame, lazy-assed alien designs/costumes, check it out if you ever have the chance. Lol!
shareYou will find that album liner on this eBay page: http://www.ebay.com/itm/STAR-TREK-THE-MOTION-PICTURE-Original-Soundtrack-LP-W-INSERT-OF-ENTERPRISE-/322373128454?hash=item4b0eef9106:g:tt8AAOSwcUBYO41K
shareI could be completely wrong so don't murder me, but I vaguely remember a friend of mine, who is a major Star Trek fan, (I am only starting to get into it) tell me that the explanation for all the doffered species looking humanoid is because all the life throughout the star trek universe derives from a single species that had left their dying home world to find a new planet to colonize....but I could be wrong.
shareThere is a TNG episode where Picard & Crew are in a Mexican standoff with Romulans, Klingons and Cardassians. They learn via holographic projection that they are all spawned from a progenitor race.
Episode is called "The Chase" - Season 6 -
https://www.youtube.com/watch?v=k-j69iVReEU
This is what you're referring to, pmtieken. It's another great scene in a series rich with them.
In The Original Series, most aliens were just humans in wacky Buck Rogers uniforms, or medieval dress, or German uniforms, or whatever. (Especially during the second season, there were several episodes where "Gee, this planet looks exactly like America during the Wild West, or the Roman Empire in the reign of Caligula, or Chicago during the Al Capone gang wars," etc.) They didn't even have funny ears unless the make up people had a budget surplus. The original Klingons were just white men in blackface; a paradox parodied on Deep Space Nine when the crew see footage of Kirk against Klingons, and say "Those Klingons don't look anything like you, Worf! What could have caused that?" and Worf says "We do not discuss it with outsiders."
shareStar Trek started out as a TV show with limited budget, so most of their aliens are actors in minimal makeup especially the regular ones like Vulcans. The original look for Klingons more or less looked like dark-skinned humans with no hear ridge.
shareYup, and the alien outfits and design was bad.. like that alien girl (Jayla?).. she looked like a clown with make-up on... geez... and her acting kinda sucked.
shareThere are simple explanations for this. First, and most important, its a matter of budget. Designing, creating and animating completely non-human species is difficult and expensive. It can be done for a major film, but week after week in a regular series it becomes prohibitive. The simple head and, sometimes, hand prostheses are much more cost effective.
The most common counter, these days, is to use CGI. Now I don't have as much of a problem with CGI as some people seem to. But it is still expensive to create one that appears realistic.
In TNG they created an in-universe explanation; a humanoid species seeded DNA into the earliest life forms throughout the galaxy so the humanoid form has become very common.
Star Trek has still had completely non-humanoid species on occasion. The horta was one (from TOS Devil in the Dark). The Shelliac was another (TNG Ensigns of Command). Species 8472 in Voyager was another.
I would love to see more non-humanoid species, but I can understand why more don't appear.