“Last night, Dad passed peacefully in his sleep after years of enduring the ravages of Parkinson’s,” the actor wrote.
“He was a true maverick filmmaker, and remained remarkably optimistic throughout. According to my stepmom’s calculations, they were happily married for just over 2000 years.”
Downey Jr then addressed his stepmother Rosemary Rogers-Downey, who tied the knot with Downey Sr in 1998, adding: “Rosemary Rogers-Downey, you are a saint, and our thoughts and prayers are with you.”
Downey Sr is best remembered for his anti-establishment work in films such as the 1969 Putney Swope and the 1972 western Greaser’s Palace, as well as his acting roles in movies including Boogie Nights and Magnolia. At the time of his death, he had suffered from Parkinson’s disease for five years.
Downey Jr’s first acting credit was in one of his father’s films, the 1970 Pound.
The actor has been best known in recent years for his portrayal of Tony Stark/Iron Man in the Marvel Cinematic Universe. He began playing the character in the 2008 Iron Man and most recently reprised the role in the 2019 Avengers: Endgame.