Lifeforce

Lifeforce (1985), possibly better known as the "Naked Space Vampire Movie," is--a very strange film. In 1985, a European Space Shuttle mission to Halley's Comet finds in the comet's tail an abandoned spacecraft with three (apparent) naked humans, two men and a woman, in suspended animation encased in glass pods. Later, after taking the pods aboard, the Shuttle goes out of contact with ground control. A rescue mission finds that all the crew are dead but the three people in the pods are still alive. The three not-really-humans are brought to Earth, whereupon they wake up, blow the hell out of the European Space Research Center, and escape. Meanwhile, the sole survivor of the shuttle's crew has returned to earth in an escape pod with a tale of terror...

And then it gets even weirder. Has to be seen to be believed.

Not to be confused with Life Energy.

Tropes used in Lifeforce include:

Badass: Col. Colin Caine. Full stop. Wandering through Vampire infected London with the full knowledge of the danger, achieving every objective and coming out alive. Yeah, Badass.
Big Bad: Space Girl.
Body Surf: After her escape the female vampire starts switching from body to body to evade capture.
Comet of Doom: The arrival of Halley's Comet foretells doom for London, as it contains an alien spaceship that carried space vampires. Discussed, as the characters mention that the appearance of Halley's Comet has been considered a warning of disaster for centuries, possibly because seeing it meant the alien ship within was near enough to allow the vampires to reach Earth and feed.
Downer Ending: The vampires are stopped from harvesting even more people by the end, but at what cost? The entire population of London is doomed, and the infection may spread even further if the army can't contain it. Carlson has either somehow turned into one of the vampires, was consumed along with the other humans' life energy, or is now captive aboard the vampire's spaceship, and Caine's chances of survival don't look too good with the remaining vampire zombies roaming the ruins of London. And the ship itself regenerates and returns to Halley's Comet, so it can return in another 95 years to do it all over again.
Evil Sounds Deep: The male vampire at the end.
Fan Service: There's a reason why the movie is popularly known as "that naked space vampire movie". This was suggested by writer Dan O'Bannon, who also put a nude girl in his next movie, Return of the Living Dead.
Fan Disservice: When space girl visits Carlson in his dreams, she proceeds to make out with him while lightning is engulfing the room and animalistic shrieks and howls can be heard all around them.
The Film of the Book: The Space Vampires
Foe Yay: Carlson is obsessed with the beautiful space vampire he is hunting, even though to touch her means death. There's even a Ho Yay moment when he's driven to kiss her while she's occupying the body of Patrick Stewart. He later discovers the reason for his obsession is that she took the image of the perfect woman from his subconscious.
A Form You Are Comfortable With: The vampires assumed human form by probing the minds of the astronauts for suitable shapes. Their real forms are the hybernating bat-like creatures in their spacecraft, notably seen when the female vampire visits Carlson in his dreams, and when the second male vampire is killed at the end.
Full-Frontal Assault: Hi there, Mathilda May. The scene where a completely nude May goes around the Research Center wreaking havoc is memorable, to say the least.
Gainax Ending: The movie makes it patently unclear what happens to Space Girl and Carlson after he stabs her at the end.
Gender-Inverted Trope: A gender inversion of the Dracula model where a male vampire with a couple of 'brides' dominates Weak-Willed females -- here we have the beautiful Space Girl (with her two male brides) manipulating the desires of Carlson and other random men. This point has been missed by those critics who accuse the film of being misogynist.
Gorn: Patrick Stewart and another guy have their internal organs burst out rather bloodily, reforming into the shape of the Space Girl.
Hey, It's That Guy! : If you're a fan of TV movie crime dramas/miniseries, you'll recognize Carlson as having played both Charles Manson and Ed Gein. Oh and Captain Picard plays the director of the Asylum.
Horny Devils: At least the female vampire operates by this method.
Horror Hunger: What human victims of the space vampires suffer--they need to drain others of life energy or they will literally shrivel up and die.
Life Energy: What the vampires feed on.
Liquid Assets: The humans' titular lifeforce.
Ms. Fanservice: The spectacularly gorgeous Mathilda May, playing "Space Girl" (really), starts the movie wearing absolutely nothing, and then graduates to wearing next-to-nothing.
No Name Given: Sorry, "Space Girl" does not count. Ditto with the other two members of her species that show up.
Not Quite Dead: The two male brides are supposedly blown to bits while trying to escape. Turned out they took over the bodies of the soldiers.
Nuke'Em: NATO quickly opens possibility of the nuclear option if the British army can't contain the vampiric outbreak in London from spreading any further.
Oh Crap: Several moments in the film, the discovery that the Prime Minister has been turned being a notable example.
Our Vampires Are Different: Turns out that the vampire myth stems from these space "vampires", who visit Earth with Halley's Comet to suck the life energy from humans.
Our Zombies Are Different: Humans fed on by the vampires become zombie-type creatures which hunt for other humans to suck lifeforce from.
Psychic Link: Between Col. Carlsen, the only survivor from the original space mission (Steve Railsback) and Space Girl.
Special Effect Failure: The zombie corpses are impressive, but they move unconvincingly.
Tomato in the Mirror: Col Carlsen is a space vampire himself. At least that's what the Space Girl told him.
To Serve Man
Vampires Are Sex Gods
Vampiric Draining: Naturally.
The Virus: A vampire zombie virus.
Zombie Apocalypse: London seriously gets out of control towards the end.