Robert Downey Jr. mourns the death of his father Robert Downey Sr.

In a post shared to Instagram, the Iron Man star revealed his dad passed away at the age of 85 following a battle with Parkinson's disease. "RIP Bob D. Sr. 1936-2021…" Downey Jr. wrote. "Last night, dad passed away 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 Variety, Downey Sr. was born in New York under the name Robert John Elias Jr. and took his stepfather's surname upon enlisting in the army. In the 1960s, he released a number of films, including Balls Bluff, Babo 73, Chafed Elbows and No More Excuses. Among them was Pound and Greaser's Palace, which featured Downey Jr. as a child. Downey Sr. also worked on TV's Sticks and Bones. In the 1980s, Downey Sr. directed Up the Academy and worked on a few episodes of The Twilight Zone. The last movie he directed was the 2005 documentary Rittenhouse Square, and his last acting role was in 2011's Tower Heist.