Emese Szigetvári, who is known as LadyFiszi on the site, is an official artist hired by Scott Cawthon to collaborate for the Five Nights at Freddy's franchise. She is known for making character arts for the novel trilogy, and also did some arts for the games like Freddy Fazbear's Pizzeria Simulator and Ultimate Custom Night along with another artist Claudia Schröder (PinkyPills).
In Freddy Fazbear's Pizzeria Simulator, a few arts from LadyFiszi are included. The logo, the posters in the alley and the child drawings in the office were made by her.
The Novel Trilogy
LadyFiszi designed the Twisted Animatronics from The Twisted Ones, and had made several artworks for them for Scott to use as teasers.
In Five Nights at Freddy's Collection, the bonus poster with Baby, William Afton and several other Funtime Animatronics who appeared in Five Nights at Freddy's: The Fourth Closet is drawn by LadyFiszi as well.
Five Nights at Freddy's: Fazbear Frights
In this book series, LadyFiszi made all the artworks in-between the short stories, as well as the covers of the books.
The cover of Five Nights at Freddy's: Survival Logbook is made by LadyFiszi, as well as the destroyed Chica art in the end of the book. Not only that, she also made the artworks throughout the book, including the Foxy drawings in-between the chapters.