Since its release last month, “Ghostbusters,” the reboot of the 1984 action comedy updated with a cast of female leads, has conjured up a series of heated debates about how women are depicted in movies and how they are treated online and in social media.

The film has also shined a spotlight on Kate McKinnon, the comic actress who plays the “Ghostbusters” team member Dr. Jillian Holtzmann, a wild-haired scientist and technology whiz who hides a mischievous sense of humor behind a pair of goggle glasses, a trench coat and a deadpan delivery. Playing off celebrated co-stars like Melissa McCarthy and Kristen Wiig, she is able to steal even the scenes in which she has no dialogue with just a gaudy grimace or a roll of her eyes.

As Manohla Dargis wrote in her review of “Ghostbusters” for The New York Times, Ms. McKinnon “makes for a sublime nerd goddess,” bringing “a dash of the young Jerry Lewis to the role with a glint of Amy Poehler.”

Like her cinematic counterpart, Ms. McKinnon, 32, seems to have been hiding in plain sight. A Long Island native and Columbia University graduate, she has become an integral cast member at “Saturday Night Live,” where, over five seasons, she has delivered reliably eccentric impersonations of Hillary Clinton, Ruth Bader Ginsburg and Angela Merkel, as well as a roster of oddball celebrities, foreigners and barflies. She received her fourth Emmy nomination in July and is poised for the kind of career breakout enjoyed by her “S.N.L.” predecessors and personal heroes like Tina Fey, Ms. Poehler and Ms. Wiig.