There is a centuries-old idea that our contribution of ‘new’ ideas to the world departs from existing foundations; we stand on the shoulders of giants.
Here are some of my (indirect) mentors:
For attention to textual criticism, classical scholarship, philology: Richard C. Jebb, Benjamin Jowett, A. E. Housman, John Sandys among others.
The crossover between the sciences and humanities, to include a suggestive and less-obvious list, the full list in my previous and upcoming work: John Ruskin, Lewis Mumford, Lane Cooper.
The breadth of the sciences, again a suggestive list: Michael Pupin, James Clerk Maxwell, Alfred North Whitehead.
Learning how to learn how to live together conscientiously, again a suggestive list: John Dewey, Paulo Freire, Neil Postman, Vivian Hodgson, Peter Goodyear. Jelena Filipović for providing necessary institutional support and opportunities for taking such an approach.
This list does not include figures like Roman Jakobson, who bring together the fields of linguistics, anthropology, philosophy, literary theory, communication, cybernetics. Mentors emerge as horizons expand.
As for contemporary mentors (in addition to Hodgson and Goodyear listed above), I will add:
Paul Graham. Seth Godin and Derek Sivers.
For Emacs: John Kitchin and Sacha Chua.
On better media design: Howard Rheingold, Mark Hurst.
Making digital technology fun, accessible, sustainable:
Daniel Temkin’s site on esolangs.
Jennifer Dewalt’s 180 blogs in 180 days; Ana Rodrigues’ “blogging and me”; NA’s “bring back the internet”; Parimal Satyal’s rediscovering the small web.