Cybertron is correct. R2-D2 is from Nabo, C3P0 is from Tatooine, and the Cylons are from wherever they come from, too, so it seems like being a robot trumps being an alien.
which is probably the best way of doing it. I personally would have been a bit confused to see R2-D2 on the aliens list. but technically he is one. as long as your definition of alien is that they come from a planet other than earth.
There are a lot of robots and aliens that could be on here... maybe to make it a bit more diverse? Right now it's very dominated by Star Wars and Star Trek.
With as many robots made popular in media I'm surprised you picked sometng obscure like the fembots. You could've done Karen from Spongebob, Glados from Portal, Jenny from Life as a teenage robot, Hal from 2001 a space odyssey or Marvin from Hitchhiker's guide. With aliens Stitch from Lilo and Stitch, Zim from Invader Zim, Xenomorphs from Alien, Predator and Frank n Fueter from Rocky Horror could be included too just so it isnt so sci fi.
I knew the Fembots but have never heard of Karen or Jenny before. Marvin would be redundant with Marvin the Martian on the quiz. The xenomorphs don't really have a proper name that's just what they're commonly called by people referencing the movies. Same with the "predators."
Actually not like the predators. They are called Yautja, so they do have a name that could be used for the quiz. How many people would got it is other thing.
Artoo for R2-D2? Threepio for C3P0?