Jacques Alexandre César Charles was a French inventor, scientist, mathematician, and balloonist.
Charles wrote almost nothing about mathematics, and most of what has been credited to him was due to mistaking him with another Jacques Charles, also a member of the Paris Academy of Sciences, entering on May 12, 1785. He was sometimes called Charles the Geometer.
Charles and the Robert brothers launched the world's first (unmanned) hydrogen-filled balloon in August 1783; then in December 1783, Charles and his co-pilot Nicolas-Louis Robert ascended to a height of about 1,800 feet in a manned balloon. Their pioneering use of hydrogen for lift led to this type of balloon being named a Charlière.