Question: who is nebula on guardians of the galaxy?
Answer: Karen Gillan

Nebula has appeared in several other media adaptations of the Marvel comics, including animated television series and video games. Karen Gillan portrays the character in the Marvel Cinematic Universe, beginning with the 2014 film Guardians of the Galaxy and its 2017 sequel Guardians of the Galaxy Vol. 2.  She will reprise the role in the upcoming 2018 film Avengers: Infinity War and the 2019 untitled Avengers film.