Matthias Koehl Jr. (January 22, 1935 – October 9/10, 2014) was an American Marine, neo-Nazi politician and writer. He succeeded George Lincoln Rockwell as the longest serving leader of the American Nazi Party, from 1967 to 2014. Like the Chilean diplomat Miguel Serrano, Koehl was influenced by the occultism of the Greek–French writer Savitri Devi. He was also a close friend of the Dutch World War II Nazi collaborator Florentine Rost van Tonningen.