Guglielmo Marconi,   Signal Hill, Nfld,   December 12, 1901.

Okay, so we're a little biased on this one! Many others, including Canadian Reginald Fessenden, had been working on similar ideas, but Marconi was the first to receive a radio transmission - the three dots of the letter "S" sent all the way across the Atlantic from Cornwall, England. His invention would lead to radio and television broadcasting, satellite transmission, cellular phones, remote control devices and much more.