Novels That Incorporate Illustrations?

[Eldan]

I don't recall The Fellowship of the Ring being illustrated. The Hobbit, certainly, but not the three LOTR books.

There are many illustrated versions of Lord of the Rings, though I think they are all from the 80s and later? That said, those of Alan Lee and John Howe were famous enough that they were basically directly used as concept art for the movies. (Google them. Some of it is basically in the movies 1:1.)