The actor’s mother, Cass Sperling Warner, was 76.

Cole Hauser is mourning the death of his mother, Cass Sperling Warner.

The Yellowstone star, known for portraying Rip Wheeler in the hit Paramount series, took to Instagram

on Thursday to share the heartbreaking news that his mother died at 76. While he did not share the cause of death, Hauser paid tribute to his mother with a sweet post that included them posing for a pic while riding horses out in the countryside.

“Her kindness, love, humor and amazing spirit will be missed by not only my family but the world,” he captioned the post. “You have touched so many. I know you will be up in the heavens sitting next to all the great humans that have passed through our earth. We will meet again. Bye for now ❤️.”

The official Yellowstone Instagram account commented on the post, “We’re so sorry for your loss, Cole. Sending love to you and your family.”

Yellowstone star Dave Annable also commented, “So sorry my friend. Sending you love.”

According to her website, Hauser’s mother was a third-generation filmmaker. Her father was the two-time Oscar-nominated writer/producer Milton Sperling. Her mother, Betty Warner Sheinbaum, was an artist and political activist. Warner’s grandfather, Harry Warner, was the original president and one of the founders of Warner Bros.

In 1993, she published the book Hollywood Be Thy Name — The Warner Brothers Story, a personal offering of her family’s deep roots in Hollywood. She updated the book in 2008 and changed the title to The Brothers Warner, which went on to become a bestseller. The book would go on to be the basis of her featured documentary, The Brothers Warner, which she wrote, produced, narrated and directed. That documentary aired for years on PBS, and it featured interviews with Dennis Hopper, Samuel Goldwyn Jr., Debbie Reynolds, Roy Disney Jr. and many more.Warner had four children — Hauser, daughter Vanessa, daughter Tao, and son Jesse.