Dad’s little son has grown up!» Kevin Costner’s son makes his debut alongside his father

Fifteen-year-old Hayes Costner is getting a taste of the spotlight, following in the footsteps of his award-winning actor father, Kevin Costner.

Hayes recently made his acting debut working alongside his dad in the film Horizon: An American Saga. Working with his father and seasoned actors like Sienna Miller and Sam Worthington, Hayes’ experience marks a memorable moment in his new career and relationship with his Oscar-winning dad.

“It felt like the greatest way that we could bond over something we both love and to create lasting memories together,” Hayes told PEOPLE in June 2024. “Working with my dad was an unforgettable moment in time.”

The movie, the first in a four-part Western epic, is set in pre- and post-Civil War United States, focusing on the expansion of the American West. Costner plays a character named Hayes, his son’s namesake, while Hayes portrays Nathaniel Kittredge, son of Frances Kittredge, played by Miller.

Horizon has been years in the making, with Costner directing, co-writing, producing and investing $38 million of his own funds into the project. Hayes noted how meaningful it was to see it all come together.

“Seeing my dad’s emotional response, hearing and feeling the audience applaud him, the standing ovation, taking it all in … it was heartwarming to see everyone appreciate the time and love he put into the film,” he told PEOPLE in June 2024 of witnessing the very warm reception his dad and the film got at the Cannes Film Festival.

Here’s everything to know about Kevin Costner’s son and costar, Hayes Costner.

Hayes is Costner’s youngest son

Hayes is the second of three children Costner had with his ex-wife Christine Baumgartner: Cayden and Grace. Costner also has three adult children with his ex-wife Cindy Silva (Annie, Lily and Joe) and a son Liam with former actress Bridget Rooney.

Five of Costner’s seven children attended the premiere of Horizon in June 2024 — at which Costner shared his gratitude for the support.

“For a studio [distributor Warner Bros.] to line up behind it to create this environment for us, to celebrate this movie we worked so hard for and one I’ve dreamed about so long, it’s pretty gratifying to understand my children are somewhere watching over me, which they always do — you can imagine that feeling,” he said.

He was involved in sports from a young age 

From a young age, Hayes was out on the field with his siblings, with Costner saying in an appearance on Today in 2016 that he and then-wife Baumgartner were in the car “constantly” going to Little League games.

“We’re trying to get the kids on the same team so we won’t have to go to three different practices,” Costner said. “So poor little Hayes, who’s in the middle, is having to play with 8 and 9-year-olds and he’s like [7], and he can hack it. So there’s gonna be this point where he’s gonna go ‘Why was I always forced into leagues?’ “

As a high schooler, Hayes plays on the volleyball team and loves to surf and fish.

His name was inspired by the role Costner went on to play

It’s no coincidence that Hayes shares a name with his father’s character in Horizon, Hayes Ellison.

Born on Feb. 12, 2009, Costner revealed that the name of his youngest son was inspired by a cowboy character in a Western film Costner was working on, at the time calling Hayes a “great Western name.”

Over a decade later, Costner divulged the significance of the namesake.

“I started [Horizon] in 1988 and I couldn’t make it but I couldn’t fall out of love with it,” Costner told the Associated Press in May 2024. “And so at a certain point in my life, 15 years ago, I just named my son Hayes because I just couldn’t let go of it. And then all of a sudden I put him in the movie.”

Costner could be “hard” on Hayes at times while filming Horizon

Costner didn’t always go easy on his son Hayes while directing him in Horizon: An American Saga. In an interview with PEOPLE in June 2024, Costner mentioned how Miller once remarked that he was “kind of hard on Hayes.”

“And I said, ‘I know. I need him to be really good, and he’s inexperienced and I’m going to help him all the way through,’ ” Costner told PEOPLE.

Still, Hayes said his father was “always gentle” when giving feedback and always defaulted back to “dad mode” at the end of the day.

Despite being new to acting, Costner praised his son for his performance and remarked how he created some “magical” moments on the screen of his own.

“I’m really proud of his performance,” Costner added.

Horizon wasn’t Hayes’ first movie premiere

In 2015, at just 6 years old, Hayes joined his mother and siblings Grace and Cayden alongside Costner at the premiere of Disney’s McFarland USA.

Also, in 2019, five of the seven kids joined Costner at the premiere of The Art of Racing in the Rain.

This time around, Hayes’ appearance in his dad’s film ignited sentimentality from both the new actor and Costner.

When asked on the red carpet about working with his father, Hayes underscored his enthusiasm for the project.

“I loved it,” Hayes told Access Hollywood at the premiere. “He just taught me everything and he was there directing by my side and it was just amazing to watch him,” prompting his father to get visibly emotional, holding back tears and Costner saying, “it feels good.”