Jakiw Palij, who was thought to be the last Nazi collaborator living in the US, was deported to Germany last year after a lengthy legal battle.
Palij had been stateless since 2003 when a federal judge revoked his US citizenship over his Nazi links.
Reports say he died in a home for the elderly in the town of Ahlen.
Before his deportation, the former guard lived in the Queens borough of New York City.
His presence there, in a particularly diverse borough, became a point of contention when his past emerged.
His home was often picketed by protestors demanding his expulsion.