I couldn't have only one as you have people doing things in different fields and they are all significant. My list of 10 would include the following and in no particular order. My choices are obviously subjective too and totally enshrouded with my own particular tastes.

1) Albert Einstein
2) William Shakespeare
3) Noam Chomsky
4) George Orwell
5) James Toney
6) Richard Dawkins
7) Kenny Dalglish
David Bowie
9) Steven Hawkings
10) Most definitely me