James Bond, although, presumably for copyright reasons, never named directly in the series, looms large in the legend, both fan-made and internal, of Rick Castle. As a literary character, he seems to have few rivals in Castle's affections, with the clear exception of Nikki Heat. He and Batman appear to be Rick's role-models, and certainly the playboy persona he displays in the pilot owes much to the two of them.
In "When the Bough Breaks", Castle himself declares this iconic character to have been "the reason I became a writer." Rick is considered and then chosen as the writer to relaunch the franchise, that is until "Heat Wave" became a hit and Rick and his publisher and agent decided to continue that series instead.