Nyx is a scout fairy who appears as the main antagonist in Tinkerbell and the Legend of the Neverbeast, primarily due to her seeing Gruff as a threat. She is the leader of the scouting-talents as she warns Queen Clarion of trouble directly and also issues orders to the other scouting-talent fairies.
Nyx's main group includes the scouts Fury, Chase, Di and Shade. She debuts rescuing Tinker Bell from an adult hawk, summoned to Pixie Hollow by the peeps of a hawk chick that Fawn had been caring for- Fawn's caretaking is mentioned by Nyx as a regular source of danger in Pixie Hollow, leading to a stern lecture.
Initially, Nyx shows some distrust of Fawn due to Fawn's habit of caring for dangerous animals close to or within Pixie Hollow--including snakes, hawks, etc. Nyx also perceives the Neverbeast as a threat to Pixie Hollow due to her misinterpretation of the legend owing to the librarian's research. She becomes insistent on hunting it, while Fawn befriends and learns about the creature. During the course of the film, she argues with Fawn many times, both pointing out the value of the other but seeing things a different way- Fawn's clearly hiding something and trying to innocently joke about the seriousness of the situation, much to the ultra-serious Nyx's frustration.
When Tinker Bell is injured by Gruff, Nyx declares an all-out assault against Fawn's wishes- finally, it's understood that Gruff is innocent (he hurt Tink while saving her life), and Nyx helps Gruff save all of Pixie Hollow from a once-a-millennium storm. She finally offers Gruff "the thanks of a grateful scout".
Nyx places the safety of Pixie Hollow's fairies above all else. She has a commanding presence and no-nonsense attitude but also softens when she is being affectionate with her friends. Nyx has skills in gymnastics, defensive flying, strategy, and fighting. Her weapon appears to be a black-and-white striped porcupine quill which matches the scouting-talent fairy uniform.