There are Halloween costumes with cheap plastic masks and thin gauzy overalls and then there are Halloween costumes that DIY types spend much more time on than is healthy for the most part. I think this awesome Halloween costume from a guy on Instructables going by "alexthemoviegeek" has created definitely falls into the latter category.
The guy built a full-size replica of the power loader Ripley used to defeat the Alien queen in the Aliens flick. The guy made the power loader to go with the life-size alien queen statue he had already created. That guy's house has to be the place to go Halloween night.
The guy based the loader on measurements taken from an Aliens Power Loader diorama and then scaled them up eight times. It's freaking awesome and I want one to wear for trick or treating. Check out the how to if you want to build your own.