Mariani C. Dimaranan (February 1, 1925 – December 17, 2005), also known as Sister Mariani, was a Catholic nun and activist in the Philippines who fought against the dictatorship of Ferdinand Marcos. Dimaranan headed Task Force Detainees of the Philippines, created in the early years of martial law in the Philippines by the Association of Major Religious Superiors of the Philippines to investigate and document human rights abuses. Her name is inscribed on the Bantayog ng mga Bayani Wall of Remembrance, a memorial that honors martyrs and heroes who fought the dictatorship.