Steven Spielberg will miss Kirk Douglas' "letters and fatherly advice".
The 73-year-old filmmaker paid an emotional tribute to the late Spartacus star - who sadly passed away on Wednesday aged 103 - and revealed the Hollywood legend has been a big inspiration on his own career.
In a statement to the Hollywood Reporter, he said: "Kirk retained his movie star charisma right to the end of his wonderful life and I'm honored to have been a small part of his last 45 years.
"I will miss his handwritten notes, letters and fatherly advice, and his wisdom and courage -- even beyond such a breathtaking body of work -- are enough to inspire me for the rest of mine."
Halloween star Jamie Lee Curtis also offered some kind words following Kirk's death, as she opened up on growing up watching him on screen.
She wrote on Instagram: "'I love you Spartacus, like the father I never had.' Antonius
"I did have a father and he LOVED you as the world loved you. Your passion. Talent. Politics. Family. Art. Strength.
"I grew up with the Douglas boys. My love to Anne and all his family from mine."
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And Lee Purcell - who starred with Kirk in 1983 thriller Eddie Macon's Run - has fond memories of their time together on set.
She said in a statement to Entertainment Tonight: "It is with great sadness and respect that I reflect upon the passing of Kirk Douglas.
"When we worked together on the feature film Eddie Macon's Run, it was a joyful and humbling experience to see Kirk, already the icon of icons for decades, come bounding onto the set each day brimming over with enthusiasm and energy.
"He set a fine example for everyone from cast to crew to execs. I have a lovely note he sent me just a couple of months ago on my office wall visible as I write this that I will always treasure.
"Bon Voyage, Kirk, you are a true mensch. My deepest condolences to Anne, Michael and the rest of the family."
The tributes came after Michael had confirmed his father's passing.
He said in a statement: "It is with tremendous sadness that my brothers and I announce that Kirk Douglas left us today at the age of 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.
"But to me and my brothers Joel and Peter he was simply Dad, to Catherine, a wonderful father-in-law, to his grandchildren and great grandchild their loving grandfather, and to his wife Anne, a wonderful husband."
As well as Spartacus, Kirk was known for the likes of 20,000 Leagues Under the Sea, Lonely Are the Brave and The Bad and the Beautiful, and shot more than 90 movies in his career.