There are a bunch of "villians" in the movie, but none of them really... work.

We have:

The Engineer- Has no discernible motivation, unfathomable goals, and basically acts like a savage animal (doesn't attempt to communicate, just tries to kill everything in the last 20 minutes).

The Aliens- In the original movies, Aliens killed people and laid their eggs. Here, it's like they're given a strange backstory of being biological weapons, and being destined for earth, but also having human DNA? Only problem is, there's no payoff- what is essentially a central plot point is left half-explained and unresolved. This distracts from their menace.

The Old Guy- Obviously meant to be a bit of a villain- pulls strings from behind the curtain, tells the female protagonist to shut up, has a Violent Bodyguard... but again, he appears too late, and has unclear motivations (does he want the Engineers to heal him? Is he a philosopher, that just wants to "meet his Makers?", and is dealt with too anticlimactically.

Vickers- Another meant-to-be-a-villain. She tells Our Heroes that they are not to engage with any aliens they find. She sets the dude on fire when it turns out he is infected by a fast-acting alien contagion. She's a bit of an ice queen. Yet, her objections are fairly reasonable, and she hooks up with the captain.



So, yeah. 4 antagonists, none of them very effective. I think it probably would have been better if most of David's actions were transferred to Vickers, and David was just in the background being helpful and a little passive aggressive.