When Harold Ramis died last week I looked for a poster to memorialize him. It wasn’t easy: Ramis was a director of American comedies, and American comedies, especially from the 1980s onwards, tend not to have the most visually arresting posters. But then I came across the poster for National Lampoon’s Vacation, a poster I had seen before but not paid a lot of attention to because its hyper-realist, exaggerated comic book style wasn’t really my cup of tea. But looking at it years later I can appreciate it as one of the last hurrahs of movie poster illustration as well as a witty parody of heroic iconography in the service of broad comedy.

The poster is the work of Boris Vallejo. Born in Peru in 1941—he came to the States at the age of 23—Vallejo is a renowned fantasy and science-fiction illustrator known for his muscle-bound heroes,...