Sun Tzu
Strategist
Sun Tzu is here because the book is mostly about not fighting. Know the ground, know yourself, and win before the battle starts. I read him when I am about to answer a problem with more force.
The Art of War is credited to a general of the state of Wu around 500 BC, though the text was probably put together later. Thirteen short chapters. What we have of his face is a modern statue, not a portrait.
Photograph by 663highland. CC BY 2.5. Source. Modern statue at the Enchoen garden in Yurihama, Japan. No portrait from his lifetime survives.