Helen Keller maybe. But I would say with INFPs being known for writing: William ShakespeareHere's some guesses:
INFP: Helen Keller, Fred Rogers
Ohh look I'm winning!
OK so I'm assuming these type assumptions come with the debatable disclamer
Helen Keller maybe. But I would say with INFPs being known for writing: William Shakespeare
EDIT: Hmmm, but if you have to cover the whole humanitarian side: Audrey Hepburn, Mia Farrow, Richard Gere, Princess Diana (not so healthy though ). But this may be rather shallow to pick an actor/royal figure...
Then there's all those religious figures...
I think I'll stick to Shakespeare.
ISFP: Steven Spielberg, Ozzy in his latter years.
Spielberg is ENFP, not ISFP.