The cause of death for Kirk Forrest Reeves, 56, is not being reported publicly, pending notification of his family, the Portland Police Bureau said in a news release.
Reeves played regularly at the west end of Hawthorne Bridge and also frequented Waterfront Park and Jamison Square, police said.
He was recognizable in his customary white jacket, glasses and Mickey Mouse ears, and often waved and smiled to police officers who passed by while he played.
Police said Reeves may have a sister in the Boston area and cousins in Los Angeles, but the medical examiner has not been able to come up with specific information to help notify his family.
Kate Middleton recycles dress at movie premiere
Jordana Brewster on Paul Walker: 'He was an enormous presence in my life'