Johannes Winkler (29 May 1897 – 27 December 1947) was a German rocket pioneer who co-founded with Max Valier of Opel RAK the first German rocket society "Verein für Raumschiffahrt" and launched, after Friedrich Wilhelm Sander's successful Opel RAK liquid-rocket launches in 1929, one of the first successful liquid-fuelled rocket in Europe.
In 1915 during World War I, he joined the German army and was wounded in action the following year, leading to a lengthy hospitalisation. After his recovery, he studied as a machinist at the Danzig technical college and found a job at Junkers.
On 5 July 1927, he was one of the founders