Joan Loumin is a mosquibee, and an important member of the dissidents. Twinsen meets him in the Otringal Prison and frees him. Later they meet again when Twinsen arrives to a dissident meeting in the souvenir shop. When Twinsen goes to the Island of the Mosquibees to meet with Queen Astrid, Joan is there with her. They meet one last time in the cell of the Building Company at the Island of the Wannies.
Joan Loumin's name comes from Jean Moulin, a famous French leader of the Résistance during World War II.