Guillermo Bolin was Spanish. He was probably with Vogue from around 1924 to 1935. The book Fashion Drawing in Vogue says "Vogue was joined in the mid-20's by Spaniard Guillermo Bolin, also the designer of some notable covers, who adopted a graphic process more fractured and dynamic but close in style, and spirit to Art Deco adventurousness. Bolin was established in New York.
In 1926, he had sketched the Barbara Lee Spring frocks. In 1931, it is mentioned that Vogue looks back at the crisp graphic style of Bolin in the later 20's with his clean lines and flattened volumes.
Above are four covers drawn by William Bolin in 1925, 1926, 1927 and 1929 for Vogue and Vanity Fair magazines.
Bolin was a prominent and versatile contributor. His major part was in the innumerable incidental vignettes and illustrations that did so much to make Vogue of those days so characteristic of its time. When American Vogue published photographs of it's illustrators in 1933, Bolin was included.