The cause was Parkinson’s disease, his wife, Rosemary Rogers, said.
His son, actor Robert Downey Jr, paid tribute on Instagram: "RIP Bob D. Sr. 1936-2021…Last night, dad passed peacefully in his sleep after years of enduring the ravages of Parkinson’s ..he was a true maverick filmmaker, and remained remarkably optimistic throughout..According to my stepmoms calculations, they were happily married for just over 2000 years. Rosemary Rogers-Downey, you are a saint, and our thoughts and prayers are with you."
‘Putney Swope,’ a 1969 comedy about a Black man who is accidentally elected chairman of a Madison Avenue advertising agency, was perhaps Downey’s best-known film.