Three people:
1. My daughter. She's not yet 5. She's inspirational because watching a small child come to grips with the world and discover it makes you look again at things you take for granted and see them as new again.
For example, I showed her the pendulum of a clock and how it swings back and forth based on its length (not the size of the weight or the angle it starts at). The length of a pendulum counting seconds is where we get the length one metre from. So time and space come together in such a simple thing. Also you can use a pendulum to show the rotation of the earth.
So many simple and beautiful things to discover. Also, the original measurement of the metre was done by Mersenne of primes fame. BTW, did you ever notice how children count things by pointing at them one by one and saying the number? That sort of counting let's you can go straight to Cantor's pairing function that the number of rationals is the same as the number of naturals. It's child's play.
(OK, better stop of I'm going to turn into James Burke: http://en.wikipedia.org/wiki/Connections_(TV_series))
2. My A level Advanced Maths teacher who told me that there was "a Group, Ring or Field lurking in every corner". He showed me the beauty of logic and studying systems specified by a few axioms.
3. When I was about 6 years old my parents took me to Cambridge for a couple of days organized by the National Association for Gifted Children (http://www.nagcbritain.org.uk/) where I remember clearly a man (no doubt a Cambridge don) explaining to me the theoretical operation of a computer. It was only years later that I realized that he had explained the operation of a Turing Machine. I was utterly fascinated.
