Geraldine Decker (March 11, 1931, New York City — June 14, 2013, Oxnard, California) was an American mezzo-soprano and voice teacher who had active singing career in operas and concerts from 1971 through 2010. She was particularly active with the Metropolitan Opera and the Seattle Opera, and is best remembered for her annual performances in Seattle of Richard Wagner's Ring Cycle from 1974-1987. She taught on the voice faculty of Pepperdine University.