LOS ANGELES — On a sidewalk across Wilshire Boulevard from the Los Angeles County Museum of Art, Steven Yeun, one of the stars of “The Walking Dead,” was handing out refreshments to passers-by just before lunchtime. The gourmet street food came courtesy of the Bun Truck, which Yeun’s younger brother Brian co-owns and operates, serving Korean-Mediterranean fusion cuisine to hungry Angelenos.

The actor stood by, helping visitors puzzle over the menu, strongly recommending the spicy pig “sammich” with a side of the duck fat fries. When it comes to potatoes, glistening and golden, studded with garlic and rosemary, he noted, it’s hard to go wrong.

Yeun’s amiable nature is familiar to fans of AMC’s hit zombie series. As Glenn Rhee, he functions as a likable everyman, the closest thing to a romantic hero in an unrelentingly brutal apocalyptic world.

“Steven is the heart of the show,” said Glen Mazzara, the “Walking Dead” executive producer who’s set to leave the series at the end of this season. “Everybody loves that character; everybody’s rooting for that character. He may be tortured and sensitive, but he’s always a hero.”

With “The Walking Dead” back for the latter half of its third season, heroes are in short supply. The show’s core ensemble of survivors led by Andrew Lincoln’s Rick Grimes has run afoul of the lethal, manipulative Governor (David Morrissey), the self-appointed guardian of a walled Southern enclave called Woodbury.

It’s there that Yeun’s character was beaten and his girlfriend Maggie (Lauren Cohan) sexually assaulted after being abducted while scavenging for supplies. Having escaped with their lives, Glenn is primed to exact revenge on the Governor for his crimes.

“It’s a heavy season for everyone,” Yeun said. “But for Glenn, I love that they’re continuing to grow a character. They’re continuing to have him complete his arc, to keep that trajectory. He starts being self-aware and realizing that it’s not just about living for yourself, it’s also about living for the people you love, and when you love somebody, that really opens you up.”

With a story line designed to explore the ways in which human cruelty can be scarier than the actions of hungry hordes of zombies, Glenn’s presence keeps the narrative from teetering into despair.