Every actor knows the old adage that there are no small parts, only small actors. And those who have worked in a group environment will agree that jobs are much more harmonious if everyone is in sync. For both of these ideas to jell, a production needs good casting directors: people who have the connections, knowledge and the sixth sense to suss out the best talent to fit into the jigsaw puzzle that is a stellar ensemble cast.

“Building the ensemble is finding actors who writers can actually go to in storylines,” says Dawn Steinberg, exec VP of casting and talent for Sony Pictures TV. She has been there for pivotal moments of TV history such as Aaron Paul nailing his audition for AMC’s “Breaking Bad” and Jeff Garlin screaming into the camera that then-ABC president Paul Lee should hire him for “The Goldbergs.”

Steinberg adds that pilots aren’t usually that long and therefore not all characters are fully developed. The goal, she says, is to have a series where “you’re going to ‘build it out,’ as they say.

“Other characters are going to come into the forefront and other characters are going to have storylines,” she says. “And other characters are going to hold their own opposite the leads. And hopefully, they will have chemistry and several episodes in the writers will go, ‘Did you see that? Those two people have great chemistry.’”

This dynamic can be easier when projects have a lead already in place; after all, as Steinberg says, “if somebody’s cast, that’s one role checked off from what you have to do.” But, in the grander scheme of things, it gives casting directors and creators an idea of what kind of talent the surrounding players will be up against.
“Once you have the lead set in a new pilot or story, then you work to cast around that in terms of the kind of actress [or actor],” says Sharon Bialy, who, along with partner Sherry Thomas, cast Hulu’s “The Handmaid’s Tale” after star and exec producer Elisabeth Moss had signed on to the series.

Bialy says they knew Moss’ reputation for being “an incredibly hard worker” and that “she doesn’t suffer fools well.” So, clearly, Bialy says, “one component of putting the ensemble together is to make sure that you have actors of a similar standard who work that way.” Similarly diligent talent including Yvonne Strahovski and Samira Wiley fleshed out that show’s dystopian universe.

Everyone interviewed for this report stresses the need for writers and directors to be able to trust that their creations are safe in the hands of a casting director, with seasoned casting director Tiffany Little Canfield (NBC’s “This Is Us”; the upcoming Hugh Jackman-starring “The Greatest Showman”) admitting that it can be scary because “it’s often the first time you’re hearing the words out loud during the process.”

If things go well, casting directors get compliments. Liz Flahive, who co-created Netflix’s “GLOW” with Carly Mensch, says of her casting director, Jennifer Euston: “She’s a unicorn who can find other unicorns. She’s very connected to us and the script, but she has a mental Rolodex of actors who she loves that you’ve never seen before.”

But the surfeit of quality projects can make for tough competition for talent, even among siblings. John Papsidera has cast all of Christopher Nolan’s movies (except 2002’s “Insomnia”), and he also casts “Westworld,” the HBO sci-fi Western from Nolan’s brother, Jonathan, and sister-in-law, Lisa Joy. He laughs when asked if the Nolans share.

“I know there’s conversations behind my back, which I think is funny,” Papsidera says. “I don’t think there’s any hard line of ‘I want to use that person, don’t use them.’ I just think it depends and it differs because you’re looking for something very different. Television requires longer deals, more commitment. That kind of separates the talent pool.”

But he believes that, because of Nolan and Joy’s script and vision for “Westworld,” “we got amazing feature actors” and “an amazing ensemble” that includes Thandie Newton, Jeffrey Wright and Evan Rachel Wood.

Not surprisingly, many see limited series as a best-of-both-worlds scenario because of the shorter contracts and buzzy moments, as when Nicole Kidman won the Emmy for HBO’s “Big Little Lies.” That gives A-listers incentive to take smaller parts in ensembles. “I love limited series so much,” says Sony TV’s Steinberg, who believes seeing the ABC miniseries “Rich Man, Poor Man” in her formative years may have had life-altering repercussions. “The fun with limited series is that … the exclusivity allows you — if you can figure out the time — to get other actors and just assemble a really great team of people: Names from theater, names from television, names from movies.”

Of course, not all ensemble parts are meant for star power. In fact, the beauty of a good ensemble part is that the character must be interesting enough, but not too distracting that audiences are mentally checking the actor’s IMDb credits. Papsidera cites Barry Keoghan, who played George in Christopher Nolan’s “Dunkirk,” as an example.

“When I first met Barry, there’s something quiet and sad in his essence,” Papsidera says. “When we started putting together the boat and who was on the boat with [star] Mark Rylance, Barry I pushed hard for, because I thought he had that essence that would break your heart. Not only was his look great and it would differentiate him from the other guys on the boat, but also there carries with him real vulnerably as a counterbalance to Mark and Tom [Hardy].”

Papsidera, who also works on Showtime’s long-running drama “Ray Donovan,” says he knows that it’s “harder to constantly try and freshen” older shows and sometimes you have to “put your dukes up and part of what I do is to convince agents and managers why their clients should be in my projects.” And certainly his casting Susan Sarandon in that series this year helped get actors in the door for smaller parts.

Sources also confirm that ensemble projects are also some of the best ways to counter a dearth of diversity and fight stereotypes. “I always look at the relationships,” says “This Is Us” casting director Little Canfield. “What are the important relationships in the script? How much do those relationships depend on archetypes: a leading man, a leading lady. We love to mess with the rules and mess with the ideas, but in order to do that you have to understand how it’s done. If you’re making a choice, you have to understand what the normal way to do it is.”

She mentions casting Justin Hartley as the show’s muscular pretty boy, Kevin, as an example because that character’s “story is he’s underestimated because he looks like a football player or he spends all his time in the gym.” Specifically, she says, “he looks like an actor. He looks like an actor on a sitcom.” She bended some rules by getting Milo Ventimiglia to play the family’s troubled father, Jack.

“The part of Jack in our original breakdown was sort of an Everyman young Tom Hanks type,” Little Canfield says. “Milo is not a young Tom Hanks type. He’s edgy. He’s got a great working-class vibe. He’s incredibly handsome. He’s really fit and all of those things. It would take him out of an Everyman type. But we reached out to him and he read the role and said, ‘I connect with that role.’ And he came in and when he auditioned, it changed our perspective of what that role would be or could be.”

And while “This Is Us” is about an extended family, Little Canfield says this part of casting wasn’t nearly as challenging as finding actors who looked like older or younger versions of the same character for the tearjerker’s notorious flashback scenes. “Sometimes I have to actually remind people, do you look exactly like your brother?,” she says.

Little Canfield also acknowledges the work of hair, makeup and costume crews who work with her to establish “This Is Us” and other projects’ period elements. She also cast Showtime’s “I’m Dying up Here,” spending nights in standup clubs on the hunt for people who “just feel like they come from a different time” and both “comedians who could act” and “actors who could do standup comedy” for this dramedy about the 1970s standup circuit in Los Angeles. Similarly, Flahive and Mensch’s “GLOW” needed to fill their women’s wrestling series with actresses who could wrestle, but who also looked like people who would not be cast in traditional roles in the early 1980s.

“A lot of casting was building forward from what we wanted to see on TV and then building backward,” says Mensch. “We’re a wrestling show and a lot of what wrestling is about is kind of taking on stereotypes and boogie men in the culture in any given moment.”

She says they needed “characters who could take us on the journey” of what it felt like to play an Arab stereotype (a part that went to Sunita Mani) or an out-of-work Blaxploitation actress (which went to Sydelle Noel). Even star Alison Brie had to fight for her role as the overly enthusiastic hot mess with the Russian wrestling persona, Ruth Wilder; the creators first wrote her off as being too pretty and together. Only Kia Stevens came with any actual wrestling experience.

Casting director Papsidera might have the most honest approach to his job.

“At the end of the day what I do and what I try to do, is match an actor’s soul and their essence to something that’s two-dimensional on a page,” he says.