Science-fiction has given us classic characters, amazing monsters and the pseudo-scientific gibberish we love. But for every visually amazing interstellar stranger (Jabba the Hutt, Dr. Zoidberg), there's another one that basically looks like a human but, you know, tweaked.

It's lazy. Face it. There are numerous "near-humans" kicking about the sci-fi galaxies, notably in Star Trek (see ol' Spock, left), with a wrinkle in the forehead here, a kink in the nose there ...

Give us real alien aliens, dammit! We're worth it. And so you know the error of your ways, here are nine classic examples of blink-and-you'll-barely-notice-the-difference "aliens."

Alien species: Kryptonians from "Superman"
Example alien: Superman, aka Kal-El, aka Clark Kent
Key difference from humans: To the eye, nothing -- he's just an especially beefy and incongruently shy, mild-mannered reporter. In the unseen-superpowers department, however, he's off the chain, with super-speed and strength, the ability to fly, laser eyes, ice breath and, well, the whole superhero kit and kaboodle. But did he look anything like an alien? Anything to give him away? At all?
Alien trivia: Originally Superman couldn't fly, he could only "leap tall buildings in a single bound."
A serious threat to mankind? If he's on our side (which he almost always is, barring unusual episodes), he's an absolute pussycat.

Alien species: Time Lords from "Doctor Who"
Example alien: The Doctor (various; famously Tom Baker, currently Matt Smith)
Key difference from humans: Similar to the Man of Steel, not that much on the surface. He can live for a very long time, can regenerate when required; has two hearts, slightly colder blood and a "respiratory bypass system" so he can't be strangled. But still, come on. He couldn't look more human, in any of his forms.
Alien trivia: Other "alien powers" include being able to read quickly, great stamina and not needing much sleep.
A serious threat to mankind? Not at all; the total opposite, in fact. He adores us, basically. God knows why.
Alien species: Orkans from "Mork and Mindy"
Example alien: Mork (Robin Williams)
Key difference from humans: Aside from being totally kerr-azy (and maybe a little hairier than most humans), adoring wacky improv, loving rainbow colors and making odd noises ... nothing! It's yet another "alien" who's just a bit weirder than most humans, but visually remains an absolute doppelganger.
Alien trivia: Orkans originally evolved from chickens. No, really.
A serious threat to mankind? If you're fatally allergic to extreme levels of improvised silliness, very high. Otherwise, no.

Alien species: Felis sapiens from "Red Dwarf"
Example alien: The Cat (Danny John-Jules)
Key difference from humans: Firstly, Cat is most definitely an alien. It doesn't matter that he evolved from a cat, it's not a human, it came from outer space, it has a science-y name ... ergo, alien. Anyway, sharper teeth, six nipples, color-coordinated body organs, a better sense of smell, a cooler heartbeat and better fashion sense is how Cat differentiates from mere humans. In other words, Danny John-Jules dressed up as Little Richard while wearing fake teeth.
Alien trivia: Cat's penis has backward pointing spines, similar to a real cat's. Sheesh.
A serious threat to mankind? He'll out-dance you, out-dress you and out-smell you, but he won't kill you. He's far too cool for that.

Alien species: Vulcans from "Star Trek"
Example alien: Spock
Key difference from humans: Emotionally colder, vastly more intelligent (and logical), and capable of death grips. Oh, and contact telepathy -- we'll give 'em that. They're also blessed with pointed eyebrows and pointy ears. But -- and this is a big but -- these are at best trivial physical differences, and though they remain oh-so-very logical, Captain, they're oh-so-very human-looking too. Seriously, time in makeup? Two ears, some sticky tape for the 'brows, and you're rolling.
Alien trivia: The Vulcan salute is based on a hand symbol used by Jewish priests.
A serious threat to mankind? That would be illogical, Captain.

Alien species: Orions from Star Trek
Example alien: Unnamed Orion girl in 2009's "Star Trek" (Diora Baird)
Key difference from humans: They're green, sure, you've got us there. Physically, that's most of the difference. They can be larger, they can be stronger, and they can even be bluer (on top of being greener), but the main non-visual difference is their magic pheromone doohickies, which make men go wild and delusional. As the females often pretend to be sexually attractive slave girls, they mainly make men very, um, aroused.
Alien trivia: Male Orions are slaves to female Orions -- though they pretend to the outside world that the opposite is the case.
A serious threat to mankind? Sexually, yessum.

Alien species: Betelgeusians from "The Hitchhiker's Guide to the Galaxy"
Example alien: Ford Prefect, aka Ix (Mos Def)
Key difference from humans: The square route of absolutely nothing. 42 – 42 = 0. QED. Or something. In other words, Betelgeusians are almost exactly the same as humans, which is made even more obvious in comparison to the double-headed, three-armed madman that is the ex–Galactic President Zaphod Beeblebrox.
Alien trivia: Ford Prefect is named after an Earth vehicle known as a "Ford Prefect."
A serious threat to mankind? No, he's mostly harmless.

Alien species: Not specifically known / humanoid alien from "The Day the Earth Stood Still"
Example alien: Klaatu (Michael Rennie)
Key difference from humans: For all we know Klaatu might have loads of funky organs inside him, and tentacles by his ankles, but from what we can gather, he looks just like a normal old human. Sure, he's got a robot and shouts things like "Klaatu barada nikto!" But, if you see him walking down the street, he's just a regular dude.
Alien trivia: His catchphrase "Klaatu barada nikto!" can be spotted on a wall in "Tron." It was also used in "Army of Darkness" and elsewhere.
A serious threat to mankind? Reasonably high, as he offers an ultimatum: Join our space club and put up with loads of robots running about the earth, or die. That's not very nice, Mr Klaatu.

Alien species: Sebaceans from "Farscape"
Example alien: Aeryn Sun (Claudia Black)
Key difference from humans: When in the presence of extreme heat, they endure something known as "heat delirium'" and fall into a sort of coma. Oh, and they can see better than humans can. Other than that, plus a few differences during pregnancy, they are humans, and you'd be very hard-pressed to tell the difference between a human and a Sebacean in a lineup.
Alien trivia: Though they hate heat, they're OK with cold. More so than humans, at any rate. Now you know.
A serious threat to mankind? Considering the while lot of them are in different dimension from Earth, not likely.