Philo Vance is a fictional amateur detective originally featured in 12 crime novels by S. S. Van Dine in the 1920s and '30s. During that time, Vance was immensely popular in books, films, and radio. He was portrayed as a stylish—even foppish—dandy, a New York bon vivant possessing a highly intellectual bent. "S. S. Van Dine" was the pen name of Willard Huntington Wright, a prominent art critic who initially sought to conceal his authorship of the novels. Van Dine was also a fictional character in the books, a sort of Dr. Watson figure who accompanied Vance and chronicled his exploits.

In the early novels, Van Dine claimed that "Philo Vance" was an alias, and that details of the sleuth's adventures had been altered to protect his true identity, even if "he has now gone to Italy to live". This claim was conveniently forgotten as the series progressed. (A few years later, the same process occurred with another fictional detective, Ellery Queen, whose authors acknowledged being inspired by Van Dine.)

As Van Dine described the character of Vance in the first of the novels, The Benson Murder Case:

Vance was what many would call a dilettante, but the designation does him an injustice. He was a man of unusual culture and brilliance. An aristocrat by birth and instinct, he held himself severely aloof from the common world of men. In his manner there was an indefinable contempt for inferiority of all kinds. The great majority of those with whom he came in contact regarded him as a snob. Yet there was in his condescension and disdain no trace of spuriousness. His snobbishness was intellectual as well as social. He detested stupidity even more, I believe, than he did vulgarity or bad taste. I have heard him on several occasions quote Fouché’s famous line: C’est plus qu’un crime; c'est une faute. And he meant it literally.

Vance was frankly a cynic, but he was rarely bitter; his was a flippant, Juvenalian cynicism. Perhaps he may best be described as a bored and supercilious, but highly conscious and penetrating, spectator of life. He was keenly interested in all human reactions; but it was the interest of the scientist, not the humanitarian.

Vance’s knowledge of psychology was indeed uncanny. He was gifted with an instinctively accurate judgement of people, and his study and reading had coordinated and rationalized this gift to an amazing extent. He was well grounded in the academic principles of psychology, and all his courses at college had either centered about this subject or been subordinated to it…

He had reconnoitered the whole field of cultural endeavor. He had courses in the history of religions, the Greek classics, biology, civics, and political economy, philosophy, anthropology, literature, theoretical, and experimental psychology, and ancient and modern languages. But it was, I think, his courses under Münsterberg and William James that interested him the most.

Vance’s mind was basically philosophical—that is, philosophical in the more general sense. Being singularly free from the conventional sentimentalities and current superstitions, he could look beneath the surface of human acts into actuating impulses and motives. Moreover, he was resolute both in his avoidance of any attitude that savoured of credulousness and in his adherence to cold, logical exactness in his mental processes.