Casting director Gayle Keller never had an agenda about working in comedy, but after starting her career on various dramatic series, including Law and Order, she has become a force in the world of comedy casting. Keller first met Louis C.K., then a lesser-known comedian, in the casting of his 2001 feature directorial debut, Pootie Tang, and for an HBO sketch show that didn’t go to series. She came onboard Louie in 2010, not knowing it would be such a hit for FX. The series has garnered her comedy casting Emmy nominations in 2014 and 2015.

For Keller, the work never stops. She is constantly attending improv and standup shows in and around New York City, and goes to the theater two-to-three times a week, scouring the city for new and exciting talent. “And it doesn’t have to be Broadway,” she says. “It can be some little old dive theater in East Village or in Brooklyn.”

Her experience in the theater world came in handy when casting Season 5’s sixth episode (“Sleepover”), during which Louie takes his daughters to a Broadway play. “Louie said, ‘I really want the top Broadway actors. I want to try and get them,’ ” Keller says. As luck would have it, Michael Cera had just done This Is Our Youth and was brought onboard with John Lithgow, Glenn Close and Matthew Broderick. Lithgow and Close would shoot for a couple hours and then rush off in time to make curtain call for A Delicate Balance, in which they were starring.

FX has given Louis C.K. full creative control of the series, so when casting Keller only consults with him. “That’s kind of a rare situation,” she says. “It’s more like a movie in a way, where the director is the person making the decisions about cast. It’s just such a small show because our crew is so small, it feels very intimate—that you’re really creating something all together.”

Despite such film and TV mainstays as David Lynch, Ellen Burstyn, Charles Grodin and F. Murray Abraham that Keller has brought to the show, she’s actually most proud of finding the two actresses who portray Louie’s daughters. “I think they turned out really well because when we cast the little one she was not even six years old,” she says. “If you cast them so young, you think, ‘Are they really going to be good?’ To see them develop as young actresses and see how good they were and they’ve become, I’m very proud of that.”

Keller also takes great pleasure in giving juicy roles to lesser-known and underrated talent. “I knew Todd Barry and Bobby Kelly before I started Louie, but it was just fun to see them develop and get more screen time and have more things to do on the show,” she says. With Louie on hiatus, Keller continues her work on Inside Amy Schumer, an untitled HBO pilot, and a pilot for Jax Media starring Michael Showalter.