Robert Hutchings Goddard

Robert Hutchings Goddard (1882 – 1945) was an American professor, physicist and inventor who is credited with creating and building the world's first liquid-fueled rocket, which he successfully launched on March 16, 1926. 

Goddard and his team launched 34 rockets between 1926 and 1941, achieving altitudes as high as 2.6 km (1.62 miles) and speeds as high as 885 km/h (550 mph).
Goddard received little public support for his research during his lifetime. Though his work in the field was revolutionary, he was sometimes ridiculed in the press for his theories concerning spaceflight. As a result, he became protective of his privacy and his work. 

Goddard pulling one of his rockets

Years after his death, at the dawn of the Space Age, he came to be recognized as one of the founding fathers of modern rocketry. He was the first not only to recognize the scientific potential of missiles and space travel but also to bring about the design and construction of the rockets needed to implement those ideas.