What was that clip from TOS ?

I'll add to your Alien Queen the creatures from the Critters series.
The Thing is still the top dog as far as I am concerned. Even the blood screams! Too cool. But, you left out good choices.
1. Alien. When it came out, there was NOTHING to compare too.
2. Babylon 5: The Shadows. Very creepy cool, alien
3. Andromeda Strain. Okay, so I have studied virology. The matrix that made up the alien virus was so out of the realm of terrestrial.
4. The aliens of Star Trek Voyager (can't remember the name) that came from a fluid universe that beat the crap out of the borg. That was the best alien since the Horta (next time, actually use a real clip from the episode!
5. Star Man. You never saw what it was, but I always wondered if it was a belligerent "Thing" Hey, it was John Carpenter!
Yeah, How could you forget Species 8472 from Voyager? (What was that TOS music video anyway?)
I believe they were going for aliens that don't even remotely look human. The creature in Alien could quite possibly be an extremely mutated human (arms, legs head, tongue, standing upright) so it probably doesn't qualify as looking totally alien.
Yea this list is definitely missing a few creatures.... most notably the Crites from the Critters series, Species 8472 from Star Trek: Voyager... and the entire Alien life-cycle (facehugger, chestburster, drone, and Queen). In fact, I'm not exactly why the Alien isn't on this list AT ALL. It remains, to this day, one of the most terrifying and realisticly-filmed creatures ever to grace the silver screen (at least, in Alien and Aliens anyway... the CGI creature in Alien3 was poorly done, the creatures in Alien: Ressurection were too obvious in their man-in-a-suit approach and the creatures in AvP and AvP:R weren't filmed properly due to bad lighting... to this day the only reason why I know what the PredAlien looks like is because of the Unrated Edition box litho).
Actually, the creepier alien from the Alien films was The Face Hugger! Especially what it was designed to do to the "victim".
Jabba The Hutt. There's one UGLY alien, for sure.
I'd still give the high nods to the creatures from The Thing and Alien/Aliens!
Forbidden Planet's ElectroCreature that was seen in the electrified fencing that surrounded the space ship was really freaky, but since it was from someones mind(a projection), is that truly an "alien"?
How about the snow monster from Star Trek? or the sand worms from Dune? Oh, and the aliens from the remake of Invaders from Mars.
You missed the opening credits here guys, "Aliens that look Alien", that means bipeds can wait outside. The Face-Hugger could make the list, but the Queens and Soldiers themselves were out, as are the Crites. Even though the 8472s were bipedal they were sufficiently 'alien' in my book to make the list. Jabba? Big slug, but two arms, two eyes, one tongue.... I'd say no. And no, the Id-Creature of Forbidden Planet (why hasn't anyone done a remake of that movie?) was a manifestation of the human mind so it isn't technically an alien.
Hmm...yeah, I think I'm going to go with the queen from Aliens.