While a lot of fans did use the opportunity to wish Mr. Costner a very "Happy Birthday," some couldn’t help themselves and got a little snarky on the post. The top comment, for example, was a joke about your “ex” wishing you a happy birthday.

Kevin Costner turns 70 on Saturday (Jan. 18), and his fans shared their mostly overjoyed reactions after the official Yellowstone account on Instagram wished him a happy birthday.

Kevin Costner's breakthrough performance in The Untouchables made him a movie star, but he wishes he'd had more experience before tackling the role.

Yellowstone star Kevin Costner is celebrating his 70th birthday today -- and he's doing so by sharing an epic throwback snap of himself on social media.