Dark Nella was an evil incarnation of Lindsay Ellis' beleagured best friend Nella. Nella met her demise during the Nostalgia Chick video "Kirk vs. Picard," after getting crushed by a ladder. Later, Lindsay reviewed the X-Men cartoon without her, then her friend Dr. C. Tease offered to clone Nella back to life. Lindsay declined the offer, then went for a lonely walk. During her walk, she encountered Dark Nella for the first time. Dark Nella not only acts more evil than the original Nella, but also a higher level of self-confidence. Her crimes include trying to kill Lindsay's friends, stuffing her in a refrigerator, and terrorizing national landmarks.
Lindsay's first attempt at turning Dark Nella back to normal involved performing witchcraft with help from the Makeover Fairy and a goth girl. After this failed, Dark Nella performed a hateful review of Tron. The real Nella's love for the movie allowed her to return, but only temporarily. Lindsay's next attempt to get rid of Dark Nella involved leading her friends (who had each evaded death one way or another by this point) in a performance of "Seize the Day" from Newsies. As Nella remembered the "fangirl squee" the movie elicited in her, she argued with Dark Nella over the morality of their deeds, and finally exploded.
Lindsay then took a lonely walk by the beach, and witnessed the original Nella emerge from the ocean. She explained that she had spent the past few months in an underwater "protective healing cocoon", while an evil clone of her tried to learn more about humanity. Reunited in white, Lindsay and Nella walked off together.
Later, Dark Nella is alluded to during Nostalgia Chick's review of Jem and the Holograms: when Nella's glasses are removed, for a moment she appears to begin to revert back to the persona of Dark Nella, taking on the voice and sending Lindsay and The Makeover Fairy into a panic to get the glasses back on her face. When the glasses are replaced, Nella returns to normal.
After Linkara has a haunting in his new house during his review of the A Nightmare on Elm Street: Paranoid comics, he asks for Nella's advice on "quasi-demonic, intergalactic forces of evil" because of her experience with Dark Nella.