Spoiler alert! We're discussing important plot points and the ending of "Alien: Romulus" (in theaters now), so beware if you haven't seen it yet. For decades, the Xenomorph has been the No. 1 big bad ...
The "Alien" franchise is an undeniable classic — a staple of the sci-fi/horror genre. The series features humans fighting for their lives as they're pitted against killer aliens with acidic blood.