Jack is large and bulky, with black hair with some white in the back and blue eyes. He always wears an orange jumpsuit with black gloves and boots. He is also seen wearing his jumpsuit hood and lab goggles with teal lenses in two episodes. It is similar in design to the one Maddie wears.
Jack is incompetent at times, even coming off as goofy, clumsy, and obsessed with ghosts. Despite this, he is actually well-meaning and quite smart, capable of building working ghost and ecto machines. He is also protective of his family, and jumps at chances for quality bonding. He is a brilliant inventor, but can come off as absent-minded. When initially activating the ghost portal he left disappointed when it didn't activate, forgetting that he installed the on switch on the inside of the portal, which was what caused the accident with Danny. Sometimes, he's had no problems going to wherever Danny is, unintentionally getting Danny in trouble or embarrassing him. He is a loving and devoted father and husband. Aside from his passion of ghost hunting, his family is still the most important thing to him. He's also been shown to be fairly narcissistic, as shown in "Forever Phantom" where he names things after himself and by the fact most of his inventions have his face like the blimp, his toast, etc.
- He is similar to Drix from Osmosis Jones, Peter Griffin from Family Guy, Homer Simpson from the Simpsons, Reed Richards from Fantastic Four, Greg Universe from Steven Universe and Donald Davenport from Lab Rats.
- Jack is the first character to speak in the entire series.
- Jack's body type and color scheme are based off of Fred Flintstone.