Give some stream of consciousness and then the answer. Karen Gillan (born 28 November 1987) is a Scottish actress, director, screenwriter and model. She played the role of Amy Pond, companion to the Eleventh Doctor, in the BBC One science fiction series Doctor Who (2010 -- 2013). She has received wide recognition for portraying Nebula in the Marvel Cinematic Universe films Guardians of the Galaxy (2014), Guardians of the Galaxy Vol. 2 (2017), Avengers: Infinity War (2018), and its untitled sequel (2019), and also played Ruby Roundhouse in the box-office hit Jumanji: Welcome to the Jungle (2017).

Answer this question: who does karen gillian play in the avengers?
The relevant information is: She has received wide recognition for portraying Nebula in the Marvel Cinematic Universe films Guardians of the Galaxy (2014), Guardians of the Galaxy Vol. 2 (2017), Avengers: Infinity War (2018), and its untitled sequel (2019), and also played Ruby Roundhouse in the box-office hit Jumanji: Welcome to the Jungle (2017).
Therefore, the answer is Nebula.