Robert Downey Sr. Dead: 'Iron Man's' Father's TRAGIC Cause of Death Revealed

Robert Downey Sr., Robert Downey Jr.'s father, has died. He was 85.

Downey celebrated his 85th birthday last month, but his fans and family never knew it would be the last time the renowned filmmaker would blow his candle.

RDJ himself delivered the news about his father's death on his Instagram account.

The "Avengers: Endgame" actor shared a black and white photo of the late director and actor alongside the caption that revealed the cause of death.

"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," he said.

The 56-year-old actor also let go of another sweet statement, saying that his stepmother and father were happily married for over 2000 years.

He concluded his post with a message for his stepmom, Rosemary Rogers-Downey, sending her thoughts and prayers, as well.

RIP, Robert Downey Sr.

The post already reached 2 million likes and received thousands of comments from RDJ's fans and supporters.

One Instagram user said, "RIP RDJ SR, thank you for gracing us with your amazing work and for giving us RDJ JR who has given us many of masterpieces in Hollywood we will greatly miss you."

"i'm so sorry rdj. i love you so much. may he rest in peace," another added.

Parkinson's disease is a type of brain disorder that affects a patient's balance and coordination, according to the National Institute on Aging. It remains unknown how bad the disease affected Downey, but the condition surely stole some of his time in the past five years.

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Despite that, he surely left everyone with gems through his most celebrated works, including "Putney Swope." The 1969 film garnered critical acclaims for breaking the stigma. It starred Arnold Johnson who played the role of the only black man on an advertising company's executive board.

In 2016, the Library of Congress selected it for the United States National Film Registry for being "culturally, historically, or aesthetically significant."

Throughout his career, he graced several notable flicks, as well, including "Pound," "Up the Academy," and "Greaser's Palace." He also directed the episodes of "The Twilight Zone."

Robert Downey Sr. is survived by his wife Rosemary, son RDJ, and daughter Allyson Downey. No details about his funeral have been released yet.

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