We meet Pixel, a small yellow kitten, in Robert Heinlein’s The Cat Who Walks Through Walls. This cat is the basis of my username and I’m always excited to meet another Pixel-owned human who got the name from this book.
I also like the possibility of new Heinlein fans. ;)
I don’t recommend this book for an intro to RAH, because about halfway through stuff starts happening that makes no sense without reading some other books first. Methuselah’s Children and Time Enough For Love, at least. The first is a great intro to RAH, the second is a bit heavy but can be done— as one of his later books it gets into some controversial ideas he liked to write about.