"Surely You're Joking, Mr. Feynman" and "The Pleasure of Finding Things Out", also by Richard Feynman.

He worked on the Manhattan Project among other things, writes in a very engaging way and shares a huge number of funny anecdotes. Yet he is also thought-provoking, for example introducing the idea of nanotechnology, explains why he is against pompous titles and posing, and how he struggled with staying creative.

Besides funny stories and grand ideas, there's also a heartbreaking personal struggle. One of those books years after reading I find myself randomly thinking about sometimes.