Leo and Diane Dillon were an amazing married illustration team! They've won the Hugo award, the Caldecott Medal (Leo being the first Black person to receive that award and they won twice in a row), and Coretta Scott King award just to name a few of their accolades. They've illustrated books such as:
The People Could Fly
Honey, I Love
Why Mosquitoes Buzz in People's Ears
Sabriel and other Garth Nix titles
The Time Quartet novels
The Chronicles of Narnia books
The fact that PoC were often the focus of their artwork and books is why I was exposed to them so much (we are a PoC home of various shades and several ethnicities and my mom kept a very diverse library for us) and why I connect with them so much. As a kid, I was happy to see books with pictures that looked like me and my family and that continued into adulthood.
I'm pretty sure that they are part of the reason I got into science fiction and fantasy (nerd mom and brother also helped). They didn't only work on science fiction and fantasy with their older titles but a good deal was. I knew the picture books they did and I think seeing their work on A Wrinkle in Time and The Halloween Tree drew me to them.
Their work still makes me feel amazing.
Leo has since passed. I wish I'd been an aggressive fan girl enough to let them know how much I love them and how much seeing brown faces on book covers meant to me. Maybe I'll write Diane one day. I'm not even scratching the surface with their work. The Art of Leo and Diane Dillon blog has a ton more if you are interested.