Puin may refer to:

• Gerd R. Puin German scholar and world's foremost authority on Qur'anic paleography
• Puin (brand) a Russian brand of canned food.

• Otto, Duke of Lorraine
• Otto, Duke of Lower Lorraine
• Otto, Duke of Lower Lotharingia
• Otto Eberhard Patronenfabrik
• Otto Eberhardt Patronenfabrik
• Otto Eckmann
• Otto Edelmann
• Otto Eduard Leopold, Fürst von Bismarck
• Otto Eduard Leopold von Bismarck, Prince Bismarck
• Otto e Mezzo
• Otto e mezzo
• Otto e. neugebauer
• Otto E. Passman
• Otto Ernest Passman
• Otto Ernst Niemeyer
• Otto E. Rössler
• Otto Eugen Schulz
• Otto Everett Graham Jr.
• Otto Everett Graham, Jr.
• Otto Fabricius
• Otto Fabritius
• Otto Fahr
• Otto Falkenberg
• Otto Felix
• Otto Felix Kanitz