I am obsessed with anything written on Albert Einstein, and I love a good picture book. This one is a great introduction, including his early academic struggles and happy personality. Easily a good research resource, it also speaks to having a growth mindset.
Neo Leo surprised me. I expected a discussion of his famous paintings (Mona Lisa, The Last Supper, etc.), but instead it focused on how his inventions predated many that are well-known to us. Art and science can go hand in hand. Another great research find for kids.