The Salt Vampire played by Sharon Gimpel in Star Trek is another spooky classic. Just don't let her corner you with a kiss or she'll suck all the salt out of your body. Wow just look at those fangs! On the other hand, The friendly alien sage, Yoda resembles a creature from folklore tales who later starred in Star Wars as a little hobgoblin famous for speaking backwards, lol. ET on the other hand shares a hopeful first encounter with humans, we've probably all dreamed about at some stage.
Last but not least are the killing alien machines which frighten the living wits out of us. Robotic versions like Arnold Schwarzenegger's Terminator and Aliens utterly heartless classic monster have distinct personalities unlike ED209 in robocop3. The Alien movies have great characters, flawed and subhuman varieties which represent the best or worst in each of us. Ash, Bishop, Call, Data are I guess the ultimate humanoid aliens, androids really.
Awww shucks I guess theres an alien in all of us.