Question: Who did the illustrations for the J. R. R. Tolkien's written works?
Paraphrase: Who did the outlines for the J. R. R. Tolkien's composed works?
SPARQL (Wikidata):  select distinct ?sbj where { ?sbj wdt:P110 wd:Q892 . ?sbj wdt:P31 wd:Q47461344 } 
Answer: Mr. Bliss