What is the crossword answer for the clue: Sci-fi staple

UFO - a 3 letter word may be the answer you are looking for!

ALIEN - a 5 letter word may be the answer you are looking for!

ROBOT - a 5 letter word may be the answer you are looking for!

ANDROID - a 7 letter word may be the answer you are looking for!

MARTIANS - a 8 letter word may be the answer you are looking for!

RHO - a 3 letter word may be the answer you are looking for!

ALIENRACES - a 10 letter word may be the answer you are looking for!

Sci-fi staple

3 Character Answers:

RHO

UFO

5 Character Answers:

ALIEN

ROBOT

7 Character Answers:

ANDROID

8 Character Answers:

MARTIANS

10 Character Answers:

ALIENRACES