Martians are Aliens that are Inhabitants of mars that can have 1 or more eyes. In the year 2023, Homer and Marge had a holiday at mars with Martian Vacations  in the episode "Holidays of Future Passed", and brought at pet martian back home.        
Homer And Marge's pet alien

Homer and Marge with their pet Martian.

Stonecutter Alien

The Stonecutter Alien.


Treehouse Of Horror Apperences

Kang and Kodos are both Martians and appear mostly on Treehouse of Horror episodes.