Sci-Fi and war were seemingly made to go hand in hand.
After all, isn't it human nature to fear the unknown? And what could be more unknown that whatever awaits us in the depths of space?
It follows logically that, if the human race was to encounter extra-terrestrial life forms, we would quickly resort to trying to kill them, because we have ultimately spent the last few thousand years doing the same to one another.
There's something about seeing it happen on other planets that is irresistible to audiences, and the implications of the genre are at once terrifying and unbelievably exciting.
But which of all the movies that tread that particular ground are the best? There are so many examples out there of humankind attempting to plant their flag elsewhere, or repelling alien races seeking to do the same on our beloved Earth, that it's sometimes easy to lose yourself in the minefield of Sci-Fi titles.
Some are poorly written, acted or executed, especially where visual effects come into play. But there are some true gems among them, and the following is a list of 10 of the best.