BURBANK, Calif. — “Bajillion Dollar Propertie$,” the Seeso streaming service’s workplace comedy about the hot young brokers of Platinum Realty, is set in a glass-and-steel tower in Beverly Hills, Calif. But the sound bites in this mockumentary, where their whining and conniving are exposed, are filmed in a cramped studio in the production offices here belonging to its creator and showrunner, Kulap Vilaysack.

Most showrunners don’t direct their handiwork, but Ms. Vilaysack, 37, is not your typical showrunner. An improv comic and podcast host, she had not previously written for series TV before creating “Bajillion,” which has its third-season premiere on Thursday, June 1.

Ms. Vilaysack (pronounced vee-LIE-sock) is part of an emerging group of first-time series creators and showrunners — especially of comedies — who are younger, more diverse and more likely to come from outside the usual training ground of TV writers’ rooms. As the number of scripted shows has more than doubled in the last several years, networks and streaming services have been mining the improv comedy, film, theater and digital video worlds, and even hiring people with no Hollywood experience.