In 1994, George Weidenfeld and Nicolson Limited produced The Illustrated Hitch Hiker's Guide to the Galaxy (ISBN 0-297-83393-6), which was illustrated. With illustrations.
It was illustrated on page 44 with Marvin standing up (0.2 MBytes), and the endpapers were illustrated with Marvin sitting down (0.5 MBytes). The text was the same as the 1979 unillustrated book. Which wasn't illustrated.
The copyright page of the book includes:
MODELS AND SETS
Marvin by JONATHAN SAVILLE
For those with a technical bent, Marvin standing up had to be scanned in two pieces. Photoshop was used to mosaic these back together, and to remove the text on the page and other blemishes.
Marvin sitting down had to be scanned in six pieces. Photoshop was used to mosaic these back together and to remove some blemishes. The vertical artifact down the middle of the image was caused by the spine of the book. When I get a chance, I will write some bespoke code to suppress this.