Sentry (Robert “Bob” Reynolds) is a fictional character and superhero appearing in American comic books published by Marvel Comics. The character first appears in The Sentry #1 (September 2000), and was created by Paul Jenkins and Jae Lee with uncredited conceptual contributions by Rick Veitch. In the late 1990s, Paul Jenkins and Rick Veitch developed an idea by Jenkins’ about “an over-the-hill guy, struggling with an addiction, who had a tight relationship with his dog” into a proposal for Marvel Comics’ Marvel Knights line. Jenkins conceived of the character “a guardian type, with a watchtower”, and came up with the name “Sentry” (after previously considering “Centurion”). Veitch suggested that the character could be woven into the history of the Marvel Universe, with versions of the character from the 1940s depicted in artistic styles matching the comics of each period.

Veitch also suggested that due to some cataclysmic event, all recollection of the Sentry would have been removed from everyone’s memory (including his own). Jenkins and Veitch decided that they would create not only a fictional history for the Sentry within the Marvel Universe, but also a fictional publication history in the real world, complete with imaginary creators (“Juan Pinkles” and “Chick Rivet”, anagrams of Paul Jenkins and Rick Veitch). Jenkins pitched the concept to Marvel Knights editor Joe Quesada. Quesada decided to commission a miniseries written by Jenkins with art by Jae Lee, with whom Jenkins had previously worked on an Inhumans miniseries.