Blessed Rupert Mayer (1876–1945) was a German Jesuit priest renowned for his unwavering commitment to social justice and his courageous resistance to Nazism. Born in Stuttgart, Mayer pursued studies in philosophy and theology before his ordination in 1899. He joined the Society of Jesus in 1900 and, after extensive training, dedicated himself to missionary work across Germany, Switzerland, and the Netherlands. In 1912, he settled in Munich, ministering to the city's growing population of migrants by providing spiritual guidance and practical assistance, such as food, clothing, and employment support. His dynamic leadership, particularly as president of the Marian Men's Congregation, significantly expanded the congregation's reach and influence in Munich.

During World War I, Mayer volunteered as a military chaplain, serving on the front lines in France, Poland, and Romania. His bravery and dedication to the soldiers earned him the Iron Cross in 1915, making him the first chaplain to receive this honor. In 1916, a grenade injury led to the amputation of his left leg, after which he returned to Munich to continue his pastoral work. Recognizing the dangers of National Socialism early on, Mayer openly criticized the Nazi regime from the pulpit of St. Michael's Church. His outspoken opposition led to multiple arrests and imprisonments, including time in Sachsenhausen concentration camp. Fearing his death would create a martyr, the Nazis eventually confined him to Ettal Abbey until the end of the war.‍

After World War II, Mayer resumed his ministry in Munich, despite his deteriorating health. On November 1, 1945, he suffered a fatal stroke while celebrating Mass on All Saints' Day. Initially buried in Pullach, his remains were later transferred to the Bürgersaalkirche in Munich due to the growing number of pilgrims visiting his grave. Pope John Paul II beatified Rupert Mayer on May 3, 1987, recognizing his steadfast faith and moral courage. Today, he is venerated as the "Apostle of Munich," symbolizing the Church's resistance to tyranny and its commitment to social justice.