Michael Douglas paid a moving tribute to his father Kirk as the legendary Hollywood star celebrated his 100th birthday party.

In front of images from Kirk’s classic films, including Spartacus and Paths of Glory, Michael said it’s not just about age, but about the life he’s lived and what he’s accomplished.

Michael Douglas, left, speaks about his father Kirk Douglas, during Kirk's 100th birthday party
(Chris Pizzello/AP)

He told the party: “One of the things that I find most incredible about dad is the third act of his life.

“After all he accomplished in his professional career and what he’s given for his country, at the point in his life where he’s faced adversity, losing a son, having a helicopter crash, having a stroke, and what he’s accomplished in this third act in his life, I find quite extraordinary.”

Actor Kirk Douglas, center, gets a kiss from his son Michael Douglas, left, and Michael's wife Catherine Zeta-Jones during his 100th birthday party at the Beverly Hills Hotel
Kirk with Michael and Catherine Zeta-Jones (Chris Pizzello/AP)

Kirk Douglas kept his remarks brief, saying: “I wonder who he was talking about? He said some nice things about someone I don’t know.”

Michael’s wife Catherine Zeta-Jones then lit the 12 candles on the cake before leading the room to sing Happy Birthday with a string quartet accompaniment.

Director Steven Spielberg, right, makes a tribute to actor Kirk Douglas, foreground, during Douglas' 100th birthday party at the Beverly Hills Hotel
Steven Spielberg gives his speech (Chris Pizzello/AP)

Steven Spielberg, who arrived late and on crutches having recently broken his foot on set, came with a very specific message.

“I wanted to come here and say I’ve been shooting movies and television shows for now 47 years and I’ve worked with the best of them and you’re the only movie star I ever met,” Spielberg said.

“There is something that you have that no one else ever had … When you watch Kirk’s performance in anything, in anything he’s ever done, you cannot take your eyes off of him. It’s not possible to look away from him.”

He added: “You’re a miracle man.”