Dr. Jillian "Holtz" Holtzmann is portrayed by Kate McKinnon in the 2016 film Ghostbusters. An engineering physicist by training, she is introduced as Abby Yates's research partner on the paranormal (replacing Erin Gilbert) and becomes the team's equipment designer, constructing their proton packs as well as a range of auxiliary weapons. Though is implied to be a lesbian (as McKinnon is in real life), Holtzmann seems to be attracted to Kevin Beckman's charisma despite his stupidity, teasing that unbeknownst to herself a bisexual woman. She is hinted to have a romantic interest in Erin, as seen in an alternate ending scene where she claims that they are dating, as well as several other instances of flirting throughout the film. Her mentor is Dr. Rebecca Gorin (Sigourney Weaver), revealed later in IDW Comics's series Ghostbusters 101 that she is a parallel universe counterpart of Dana Barrett.
In the novelization, it is revealed that she narrowly missed being admitted to CERN. Several of her peers in school started calling her by her last name because "Jillian" sounded too feminine, and by the time of the film she almost never answers to her first name. She shares traits with Egon Spengler for both are intelligent and tend to do strange things.
Director Paul Feig confirmed in an interview with The Daily Beast that Holtzmann was supposed to be a lesbian, or somewhere on the LGBT+ spectrum, but the studio refused to allow that detail into the movie and instead left the audience with the freedom of more personal interpretation of her character. She was also observed by some viewers to depict autistic traits, or more specifically, someone with Asperger syndrome.