Reynolds was set to appear in the upcoming Once Upon a time in Hollywood before his death at the age of 82 earlier this month.
Dern, also 82, will take over the role, Entertainment Weekly confirmed.
The Hateful Eight actor will portray George Spahn, a blind rancher who owned the property that Charles Manson and his followers were living on when they plotted the infamous murder of Sharon Tate and her friends. Tate was more than eight months pregnant with her and director Roman Polanski’s child.
Dern and Reynolds worked together multiple times over their careers including on the 1965 TV series 12 O’Clock High and in 2003’s Hard Ground, which Reynolds directed.
Reynolds never had the opportunity to film scenes for the film, a source confirmed to PEOPLE. The star’s niece told PEOPLE in a statement, “My uncle was looking forward to working with Quentin Tarantino, and the amazing cast that was assembled.”
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The film icon died at Jupiter Medical in Florida, according to manager Erik Kritzer.
Once Upon a Time in Hollywood is opening summer 2019.