I should say three of them:
a. Philippe Flajolet
His work on analytic combinatorics inspired me enough to decide to study mathematics further after having majored in theoretical computer science. He wrote a book along with Sedgewick called analytic combinatorics, not to mention lots of papers on analysis of algorithms using the techniques he developes, he's a Cauchy of modern combinatorics.
b. Lucjan Jacak
Mathematician & quantum physicist, his lectures from quantum physics have inspired me to study this field for over two years. His most famous work concers quantum dots.
c. Bollobas, Kozma, et. al
And their work on non-constructive, probabilistic methods in graphs, also neuropercolation theory etc. Somewhat a revolutionary idea.