Charles Darwin for making the case for evolution, David Attenborough for educating the masses about it., Galileo Galilei for sticking it up the inquisition, Edwin Hubble for his work on redshift and general asrtonomy, Louis Pasteur for the betterment of mankinds, medicine and one from my childhood, Kenny Roberts snr for being a great bike racer,a great team boss and then even a (not quite as good) race bike constructor.
He has been a driving force in motorcycle racing for decades.
But most of all, Charles Darwin. A man worth of being on the face of a banknote if ever there was.