[2] He is best known for his work as a researcher at the two main American comics companies, DC and Marvel, where he helped to catalog the various fictional characters that comprised their respective continuities, including Victor Timely.

His missives impressed DC Comics editor Julius Schwartz enough for Schwartz expand the letter columns in some titles to a second, separate page (such as "Flash-Grams — Extra", "Letters To the Batcave — Extra", and "JLA Mailroom — Special Peter Sanderson Edition") to facilitate Sanderson's analysis.

Instead, the two series were prose chronicles of the fictional histories of comic book characters, which Sanderson culled from previous titles Marvel had published over the years.

[8] Outside of his online writings, Sanderson has also had a number of books published (including The Marvel Vault and The Marvel Travel Guide to New York),[9] taught the class The Graphic Novel as Literature at New York University,[10] curated an exhibition on Stan Lee for the Museum of Comic and Cartoon Art,[11] and reviews the latest in comics and comics-related material for Publishers Weekly.

In April 2017, Sanderson contributed a segment of a retrospective article on his late mentor Mark Gruenwald for Back Issue!