Sophie Scholl and her brother Hans
"One associate of the White Rose said later that Hans Scholl and Alexander Schmorell were the minds of the White Rose (because they were the principal authors) but that Sophie was its heart. She helped to copy, distribute, and mail the leaflets and was also in charge of the group's finances, which included buying paper and stamps from many different post offices so as not to create suspicion.
For suspicion there certainly was. The Gestapo was desperate but unable to discover the pamphlets' authors. They called on anyone who received a leaflet to turn it in or face immediate arrest. The Gestapo thought the perpetrators must be a large group. Little did they know that the most active members of the White Rose totaled a mere six people!"
Excerpt from "Sophie Scholl and the White Rose" from Women Heroes of World War II: 26 Stories of Espionage, Sabotage, Resistance, and Rescue.