The man known as Papa Smurf due to his distinctive blue skin and white beard has died after a heart attack and stroke.
Paul Karason, 62, passed away in a Washington hospital and had been suffering from pneumonia. His death was unrelated to his strange medical condition argyria which caused the blue tone in his skin.
Karason rose to fame when he appeared on NBC's Today programme in 2008 after living as a recluse.
His widow Jo Anna Karason said children would call him Papa Smurf because of his resemblance to the chief Smurf from the 80s cartoon.
"It was a nickname he didn’t appreciate, depending on who said it,” she said.
“If it was a kid who ran up to him saying ‘Papa Smurf,’ it would put a smile on his face. But if it was an adult, well...”
Karason began turning blue around 15 years ago after he used a silver-based formula to treat dermatitis.
He also drank colloidal silver, a treatment made of silver particles suspended in liquid.
Silver was an effective folk remedy for hundreds of years because of its antibacterial properties but went out of fashion in the 1930s when penicillin was developed.