Carl Weathers starred alongside Tony Burton in the Rocky films. Weathers played the role of Apollo Creed, while Burton starred as Tony “Duke” Evers, a boxing trainer.

Tony Burton, trainer in 'Rocky' films, dies at 78 https://t.co/15n0dXYztB pic.twitter.com/Lz6ldyC29e

— CNN (@CNN) February 26, 2016

On Thursday, Carl Weathers shared some sad news about his friend and former co-star. He confirmed his passing via social media, when he retweeted the following.

Sad news to hear about Tony Burton ? every Rocky fan loved you. RIP Duke. ?@TheCarlWeathers @TheSlyStallone pic.twitter.com/QrJTP6pyYB

— Ellis (@EllisG96) February 27, 2016

In addition to Carl Weathers, Tony Burton’s younger sister, Loretta Kelley, also confirmed his death. She told M Live her brother spent time in and out of the hospital throughout the past year, however she didn’t say what ultimately caused his death. Tony Burton was 78.

Sylvester Stallone joined Carl Weathers in paying tribute to Tony Burton.

“Tony Burton who played the character of Duke brilliantly in all six Rocky movies… Rest in peace,” he captioned the following photo.

A photo posted by Sly Stallone (@officialslystallone) on Feb 26, 2016 at 2:16pm PST

Many other celebrities paid homage to Tony Burton via social media, too, as they recalled his talent. His passing was more than that to Sly Stallone and Carl Weathers, however. They are mourning the loss of a dear friend.

Rocky star Tony Burton has died at the age of 78: https://t.co/yGxcGFq5wv pic.twitter.com/KlPaa81Vey

— Us Weekly (@usweekly) February 26, 2016