Lifeforce (1985)

This sci-fi horror film throws a lot of stuff together: it begins in outer space and the first 15 minutes are similar to the early scenes in ALIEN (1979); later, the 'vampires-from-space' scenes on Earth resemble such zombie films as DAWN of the DEAD (1978) and other similar monster films; later scenes recall scenes from POLTERGEIST (1982) - suggesting possession, spirits in movement, the light shows (and being Hooper's previous film); and, the last act is an apocalyptic end-of-the-world scenario. In light of all I just described, the film has to be at least somewhat interesting. But, the first act may be a bit derivative of ALIEN; here's what I mean:
Well, except for the nude 'Space Girl' - there was nothing like that in ALIEN. And, though the film, like a few others in the eighties, seemed to follow in ALIEN's footsteps, it also may have influenced later films like EVENT HORIZON (1997) and SUPERNOVA, not to mention the HELLRAISER films and others I can't think of now. This was written by Dan O'Bannon - yep, the ALIEN writer (based on a novel The Space Vampires; hm, wonder if the sixties film PLANET OF THE VAMPIRES-1965 had any influence?). O'Bannon was really on this 'Horrors From Outer Space' kick but might have been a big influence on the direction sci-fi films took in the eighties & nineties. However, whereas all these other films stayed in their outer space region where we expect them to - astronauts encounter threat in deep space and so on - this one switches to Earth early on and only returns to outer space in a few flashbacks.
LIFEFORCE also presents a few interesting ideas: besides suggesting the 'true' origins of the vampire legend, it also hints about the true nature of what many think of as a soul. In the context of this film's story, life is more malleable than we think; it can be drained from a person, but then returned, thereby returning the person to life (the essence of vampire mythology in the movies). The scene that sticks out to me is the one of the young soldier returning to life after draining a doctor; he looks as surprised as anyone else, but also elated in the first few seconds of being alive again and maybe a bit mad. It's a memorable few moments.
Also, I'd forgotten as to why the three aliens found on that alien spaceship looked like humans; as I watched this again, I found that an explanation is provided (now, now, we don't want to give everything away). The female-shaped alien is the one we see the most of (can't complain - oh, yes, another later film I'm now reminded of - SPECIES (1995), which featured a nude Natasha Henstridge in several scenes). Mathilda May spends most of her scenes in the nude in LIFEFORCE. Ah, Mathilda, Mathilda... if only you weren't a space vampire...  
Patrick Stewart, soon-to-be Capt. Picard on TNG, appears only after the 2nd hour begins and his scenes are rather brief; and, he spends much of them on his back, semi-conscious. He plays the enigmatic head of an asylum, of all things. This isn't all that great a film, however. It gets a bit murky at some points - near the end, the hero (Railsback) is told by the Space Girl that he is like her, that he always has been (wha..?). The film is on the slow side for about half-an-hour near the middle and the conclusion is anti-climactic, abrupt and unclear. BoG's Score: 6.5/10