Hopper is buried in Rose Hills Memorial Park in Whittier, CA.
Hopper had a bit part as a reporter in the classic 1941 private eye drama The Maltese Falcon.
In his early career, Hopper was frequently billed under the name DeWolf Hopper, Jr.
Hopper had one child: a daughter named Joan.
Hopper was residing in Yucca Valley, California at the time of his death.
Like fellow cast members Ray Collins and William Talman, Hopper was a heavy smoker in real life and this habit might have contributed to his premature death from pneumonia at age 55.
Hopper won a Bronze Star for his service with the Coast Guard in World War II.
Hopper enlisted in the Coast Guard at the start of World War II where he served as a frogman.
Hopper was nominated for an Emmy for Best Supporting Actor in 1959 but didn't win.
In one episode of Perry Mason, Hopper's character, Paul Drake, was defended on a murder charge by Perry.
Hopper and his wife separated during the course of Perry Mason's run but they later reconciled.
Hopper appeared briefly as Claire Trevor's husband in the 1954 disaster flick The High and the Mighty.
One of Hopper's best film roles was as the father of the title character in The Bad Seed.
He tested for the role of Perry Mason. Mason creator Erle Stanley Gardner, who had final say over casting, saw Hopper's test and thought him wrong for the part but mentioned that he thought Hopper would make a good Paul Drake. Hopper was brought back in, read for the role of Paul Drake, and got the part.
William Hopper is no relation whatsoever to actor Dennis Hopper.
Hopper had a flair for comedy that some of his fellow Perry Mason cast members lacked and thus his character of Paul Drake provided much of the comedy relief on the show.
Hopper and his mother had an agreement that she would never mention him in one of her columns because he didn't want anyone to think he was using her to advance his career.
Hopper once swore off show biz and took a job as a car salesman. He quit this job in a dispute with his employer over sharp business tactics such as rolling back car odometers.
Hopper's father, DeWolf Hopper, was a stage actor famous for his rendition of Casey at the Bat.
Hopper pretty much retired from acting after Perry Mason completed its run. His only listed credit is as a judge in the 1970 clunker Myra Breckinridge.
Hopper's most famous film role was as Natalie Wood's father in the classic youth angst film Rebel Without a Cause.
William Hopper: I don't dislike movie people but they were nothing special to me. I'd been around them all my life.
William Hopper: I didn't dislike movie people, but they were nothing special to me. I'd been around them all my life. My mother's the kind who could say "Howdeedo" to the king of England and feel perfectly at home. But I couldn't.