Two-time Oscar winner Michael Douglas, the eldest son of Hollywood icon Kirk Douglas, paid tribute to his father Wednesday in officially announcing his dad’s death at age 103.

“To the world he was a legend, an actor from the golden age of movies who lived well into his golden years, a humanitarian whose commitment to justice and the causes he believed in set a standard for all of us to aspire to,” Douglas wrote on social media. “But to me and my brothers Joel and Peter he was simply Dad, to Catherine [Michael Douglas’ wife Catherine Zeta-Jones], a wonderful father-in-law, to his grandchildren and great grandchild their loving grandfather, and to his wife Anne, a wonderful husband.”

Michael Douglas was born in 1944 in New Jersey, the oldest child of Kirk and actress Diana Dill. The couple had another son after Michael, Joel. Peter and Eric Douglas were Michael’s half-brothers with Kirk Douglas...