The phrase "great illustrator" refers to a person who is extremely skilled at creating drawings or images that can tell a story or depict something in a visually impressive way. Full definition
We've worked with so many great illustrators and clients over the years. (creativeboom.com)
However, the great illustrator Zdeněk Burian, in the 1960 book Prehistoric Man, still portrayed them as hairy, ape - like throwbacks, in this scene of a Neanderthal encampment. (abroadintheyard.com)
Here's a wonderful image of them by the great illustrator Carl Buell, which is now on display at the Smithsonian. (reviverestore.org)