'Risky Business' and 'The Breakfast Club' Actor Ron Dean Dead at 87

Ron Dean, famous for his work on "Risky Business" and "The Breakfast Club," is dead.

The veteran actor died Sunday at a hospital in Chicago ... according to Maggie Neff, Ron's partner of 40 years.

The cause of death is unclear, but Maggie tells us Ron has been battling a long illness.

She tells TMZ ... "He passed at exactly 4 PM, after his beloved sisters had said their goodbyes. He hung on like a warrior to say goodbye to his little sisters. Then we were alone, and in my arms, I held his hand, and he trusted me when I told him that it was alright to let go. What an honor!"

Ron often played law enforcement on the big screen and one of his first acting credits was "Risky Business," alongside Tom Cruise. He also worked with William Shatner in "T.J. Hooker," and had a role on "The Package" with Gene Hackman and Tommy Lee Jones.

He played Emilio Estevez's father in "The Breakfast Club" ... and Christopher Nolan also tapped him for a role in "The Dark Knight."

Ron's TV credits include "NYPD Blue," "Murder, She Wrote," "ER," "Chicago Hope," "CSI: Crime Scene Investigation," "Cold Case," "Frasier," "Without a Trace," "The West Wing," "Still Standing" and "Numb3rs."

He was 87.