Article Detail Who invented Vitamin K ? Answer: Doisy Dam of U.S.A. in 1938. Similar Questions : 1. Who invented Refrigerator ? Answer: Oliver Evans in 1805 2. Who invented Helicopter ? Answer: Igor Sikorsky 3. Who invented Aspirin ? Answer: Felix Hoffmann invented Aspirin 4. Who invented HIV ? Answer: Dr Robert Gallo invented HIV test 5. Who invented Air Conditioning ? Answer: Willis Carrier in 1902 6. Who invented Ball-Point Pen ? Answer: John J. Loud of U.S.A. in 1888 7. Who invented Bleaching Powder ? Answer: Tennant of Britain in 1798 Read more from - Important Inventions