Are there any other "big name" actors like Bruce Willis that had a very tragic and surreal end to their careers?

I mean, he was never an actor (or Martial Arts specialist), but Steven Seagal is one name who comes to mind. Of course, he was never a big star, but there was a short time he was well recognized and nowadays he is mostly a Putin chill. Kind of like Dennis Rodman is to his pal Kim Jong Un.

Peter Falk also suffered from Dementia, and later in life could not even recall his Columbo persona.

Rita Hayworth. She suffered from alcoholism, which for some time masked the symptoms of Alzheimer's disease as she got older. By 1972 she wanted to retire, but needed money, and took a role in a movie called The Wrath of God, with Robert Mitchum. Apparently the shoot was a very difficult one, owing to her deteriorating health and cognitive abilities. She couldn't remember her lines, and they had to feed her her lines one scene at a time during the production.

Thomas Jane
Alec Baldwin
Aaron Eckhart

Muhammad Ali. Really sad to see how he degraded.

Warren Beatty would come to mind, he did a really bad movie called “Town & Country” (2001), filmed in 1998, and again in 2000, it flopped, he didn’t make another movie for -5 years until “Rules Don’t Apply in 2016. He says he would make a Dick Tracy sequel, saying it for years since he owns the rights but that will never see the light of day.

Michael Madsen
Tom Sizemore
Eric Roberts

Bruce Lee. I'm honestly surprised no one's mentioned him here yet.