Eldar were familiar to many Imperial citizens, since they were often depicted as weakling aliens crushed beneath the feet of conquering humans in stained glass windows or in the margins of illuminated prayer books. The truth was that no human artist could ever realise one properly. An eldar looked almost human from a distance: two arms, two legs, two eyes, a nose, a mouth, but everything else was different. An eldar radiated wrongness, from its huge, liquid eyes to the many jointed, worm-like waving of its fingers.
Aw, Mom, he's no E.T. He doesn't even look like Mr. Spock!
— Sean Donovan, upon seeing the first alien Visitor in V
Every now and then when I'm watching the shows, the aliens will shake hands with one another and stuff like that, and my head starts to explode. Then again, I guess the shows aren't really about that. We're not writing books where you can spend a whole three volumes creating these deep alien cultures. But those handshakes, and asking for glasses of water and stuff! Man!
—Ira Stephen Behr on Star Trek
The original series got away with people who looked exactly like humans because it was a low budget 60's TV series. This is a multi-million dollar movie. Buy some damn forehead bumps or something!
Lady Christina de Souza: You look human.
The Doctor: You look Time Lord.
What, you think Earth is the only place humans come from?
—Andros, Power Rangers in Space
Asher: And now I'm sure you're going to ask why people from another world look so much like you...
Sir Gerard: Why would I ask that? [...] God created man in his own image. Why would he do other worlds differently?
Asher Well, I'll be damned.
Amy: And you're an alien.
The Doctor: Well, in your terms, yeah. In my terms, you're an alien. In quite a few people's terms, probably.
Amy: What kind of alien?
The Doctor: Well, you know, a nice one. Definitely one of the nice ones.
Amy: So you're like a... a space squid, or something... Are you like a tiny little slug in a human suit?
The Doctor: ...
Amy: Is that why you walk like that?
Doctor Who, "Meanwhile in the TARDIS"
Trekkie: Why is it that all of the guest stars are humanoid in shape even when they're playing aliens?
Marina Sirtis: When we start auditioning actors that are not humanoids in shape, that, of course, will change.
Fan encounter recounted by Marina Sirtis