'Smokin' Joe Frazier -- Dead at 67

"Smokin" Joe Frazier died this evening after battling liver cancer ... according to the boxing legend's agent.

The former heavyweight champ was diagnosed just last month with liver cancer.

Darren Prince tells TMZ Frazier passed away at home in Philadelphia just over an hour ago. He was surrounded by his family.

Joe fought Muhammad Ali three times in the 70s ... defeating him in '71. Their last battle was the legendary "Thrilla in Manilla."

Joe Frazier was 67 years old.