Yeah... Sorry, but when I think abut the fact that the aliens would come from a planet that orbits a different star, said planet would would almost certainly have different gravity, different composition of elements, different path to life... I can see no reason what so ever that they would be humanoid.
Most of the ET's out there are of the humanoid kind...which is why we are how we are. Our genetic makeup did not originate on earth...there are thousands of other humanoid races out there all throughout the universe. And who's to say that they would all be 3rd-dimensional beings? A lot of the ET phenomena falls under the extra-dimensional category. When dealing with 4th, 5th, 6th dimensional beings and up, they fall under a very different "physical" existence...or lack there of, I should say, haha. Being that these beings are pretty much pure energy and consciousness, they can withstand any environment they subject themselves to, since they operate outside the rules of matter and gravity that we find here on earth.