Neftis was a supporting antagonist of Underfist: The Series, the cancelled spin-off show of The Grim Adventures of Billy & Mandy series, and was going to be the secondary antagonist of the 2010 cancelled movie Underfist Against the Astrovampires.
Neftis would have been the daughter of Anubis, the Egyptian god of death. A mummy hunter, it was Neftis' responsibility to hunt down every mummy who escapes their tombs to cause messes so they would return to their tombs and stop making Anubis look bad.
After finishing The Grim Adventures of Billy & Mandy, Maxwell Atoms started to work on Underfist: The Series, a new television show for Cartoon Network. Planning it as an spin-off of the series, featuring Irwin, Hoss Delgado Jeff the Spider, Fred Fredburger and General Skarr in the lead roles, Atoms decided to make a pilot movie entitled Underfirst: Halloween Bash. With the movie's Halloween 2008 release date still waiting, Atoms began to plan the characters for his newest show, and among them, he created the rogues whom the Underfist superhero team would have to face. One of them was going to be Neftis, and as a result, was included making a cameo in the pilot movie's end credits.
According to Atoms' notes, Neftis would have been the daughter of Anubis, the Egyptian god of death. As many mummies escaped from their tombs and caused messes outside, this made Anubis look bad, leading Neftis to hunt down every mummy to deliver them back to their tombs. Taking his into account, it can be deduced that Neftis would be served as a personal enemy for Irwin, as he is half-mummy and half-vampire. However, as a little girl, Neftis would also have an interest on ponies and makeup. She was also going to have an assistant named Winkie.
Aside her role as supporting antagonist in Underfist: The Series, Neftis was going to be the secondary antagonist of the 2010 planned movie Underfist Against the Astrovampires, the sequel to the also planned Underfist versus the Dinosaur and where Neftis was planned to make her first appearance.. According to Atoms, the film's plot had Underfist meeting Neftis while discovering more about Dracula's supernatural origins while Lord Malefactor became involved in their mission.
Unfortunately, despite all his plans for the show, Maxwell Atoms was ultimately unable to carry them out because his contract with Cartoon Network expired in 2008, aside that Stuart Snyder, the network's newest president, desired to have more live-action shows in Cartoon and no spin-offs, leading to what eventually became known as Cartoon Network's Dark Age. This consequently led Underfirst: The Series to be cancelled and left Underfist: Halloween Bash as the finale of the Grim & Evil franchise.
- While never appearing in The Grim Adventures of Billy & Mandy, Neftis' father Anubis appeared in the seventh season episode "King Tooten Pooten" drawn on a hieroglyph in the Endsville Museum.