Spy thrillers have many tropes, but the most consistent I found were silhouettes, women, and eyes. The silhouettes vary between men and women, but eliminating a person's features gives a sense of mystery. It adds the spy element. The women are typically hyper sexualized. I found a wide variety of eyes, but they were almost always close up and never looking at the reader.
A few others that I found that may or may not be in the examples below are guns/smoking guns, eye glasses/binoculars, and the "spy hat."
