One of the most iconic aspects of the James Bond film series is the fact that the actor playing 007 changes every few movies. For decades, each installment in the series served as a standalone story, with very little acknowledgment of the events of other films. Beginning with 2006's Casino Royale, the Daniel Craig-starring Bond films have become much more interconnected, with major plot elements and characters carrying over from one film to the next.

Due to the series' initial lack of a tight linear continuity, a fan theory that attempts to explain the various recastings of 007 has become fairly popular. The theory posits that the name "James Bond" is actually a codename assigned to whichever agent is currently taking up the position of 007. Despite this serving as a fairly plausible explanation on the surface, several small but important elements do carry over across the series and prove that James Bond is the same character in almost every film.

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Daniel Craig James Bond Spectre

The most major of these recurring elements is Bond's wife, Tracy. She appears in On Her Majesty's Secret Service, where she falls in love with Bond and helps him defeat SPECTRE leader Ernst Stavro Blofeld. The movie tragically ends with Tracy being gunned down under Blofeld's orders shortly after she and James are married, but she continues to be referenced throughout the series, even though On Her Majesty's Secret Service is George Lazenby's only appearance as James Bond. Her death is acknowledged in several other films, and Bond is even seen visiting her gravestone in For Your Eyes Only, which also shows Bond defeating a Blofeld-esque character shortly afterward as a callback to his role in Tracy's death.

While On Her Majesty's Secret Service is ultimately a major factor in debunking the codename theory, the film also perpetuates it during its cold open. After saving Tracy from some goons, only to have her run off on him, Lazenby's Bond quips, "This never happened to the other fella." Many have seen this as confirmation of the codename theory, but in reality, the quip is likely nothing more than a short joke to break the fourth wall and put a cap on the scene, especially considering Bond breaks the fourth wall further by looking into the camera right after delivering this line.

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Pierce Brosnan as James Bond

There are several other major holes in the codename theory, with one of the biggest being that several other characters also change actors throughout the series. The biggest offender of this is Blofeld, with the character being portrayed by a different actor every time he appears on-screen (before Daniel Craig's Bond films). In Diamonds Are Forever, Blofeld is even played by Charles Gray, an actor who previously appeared in a different role in You Only Live Twice. While no explanation is given for these changes, it seems pretty clear that these are supposed to be the same characters throughout the series.

Skyfall clears up the codename theory once and for all by bringing audiences to Bond's family home and even showing off the graves of his mother and father. While the film is set in the rebooted universe of Daniel Craig's Bond films, this still seems to be a pretty clear inclination that the character of James Bond is and has always been intended to be one person. With the soon-to-be-released No Time To Die serving as Craig's final outing as 007, a recast is imminent. Only time will tell if the new Bond will pick up where Craig left off, or if the slate will be wiped clean yet again.

Directed by Cary Joji Fukunaga and starring Daniel Craig, No Time to Die arrives in US theaters Oct. 8.

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