Karen Gillan talks Nebula in Guardians of the Galaxy 2, teases Avengers appearance Actress Karen Gillan is set to return to the cosmos of the Marvel Universe with this year’s Guardians of the Galaxy Vol. 2 as the cyborg assassin Nebula, and speaking with TheWrap, she previewed a bit of what we can expect from her character in the sequel. “What I love about the second movie for Nebula in particular is that we get — We know that she’s a pretty angry woman with some daddy issues.