Shepard passed away at his home last week in Kentucky after complications from amyotrophic lateral sclerosis, the disease known as ALS or Lou Gehrig's disease, Boneau said.
“The family requests privacy at this difficult time," Boneau added. Funeral arrangements will be private.
Shepard, whose work spans over five decades, was nominated for an Oscar in 1983 for his role in "The Right Stuff," but he also had a very successful career off-screen.
He won a Pulitzer Prize for Drama in 1979 for his play "Buried Child," one of 40 he wrote over the years.
The Illinois native began his acting career in the early 1960s working Off-Broadway, before moving to Broadway and the big screen in the 1970s and 1980s. Some of his most notable plays include 1980's "True West" and 1983's "Fool for Love."
On the silver screen and TV, Shepard followed up "The Right Stuff" with "Steel Magnolias" in 1989, "Dash and Lilly" in 1999, for which he earned an Emmy nod, and "Black Hawk Down" in 2001, among a slew of other projects.
More recently, he starred in Netflix's "Bloodline" in 2015 and was in this year's film "Never Here," which hit theaters in June.
Outside of acting, Shepard was linked to Emmy-nominated Jessica Lange from 1982 to 2009 and the duo welcomed two children. He also has a son from a previous relationship.
Shepard is survived by his three children, Jesse, Hannah and Walker, and sisters Sandy and Roxanne.
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