Die Another Day is often cited as the worst movie in the James Bond franchise, but things may have been different if a planned cameo by Sean Connery's James Bond went ahead. Released in 2002, Die Another Day was the final appearance by Pierce Brosnan as 007. Despite being the highest-grossing Bond film up until that point, it was criticized by fans and critics alike for its reliance on CGI and for being overly campy and ridiculous. Featuring invisible cars and the planet-carving Icarus beam, it was hardly surprising that future entries in the series relied on the more down-to-earth, bleaker Daniel Craig Bond era.
As well as being Pierce Brosnan's final Bond movie, Die Another Day also marked the 40th anniversary of the franchise. It featured numerous callbacks to previous films, such as Halle Berry invoking Ursula Andress' look from Dr. No and the various gadgets featured in Q's warehouse. The Icarus beam itself is an overblown callback to the laser that once threatened Sean Connery's Bond in 1964's Goldfinger. However, the anniversary celebrations almost extended to featuring a cameo appearance by the original James Bond himself.
Before Die Another Day's release, director Lee Tamahori spoke of his desire to have Connery feature alongside Brosnan in the movie. Sean Connery would not have played a tongue-in-cheek version of James Bond as in The Rock; he'd have fully reprised his role. Tamahori was operating under the belief that James Bond 007 was merely a codename, and each actor who played him was playing a different secret agent that shared the prefix. This would have been emphasized in Tamahori's original Die Another Day concept when Brosnan's Bond is let go from MI6, only to meet another former 007 agent, Connery's Bond, who eventually serves as his mentor as the Brosnan Bond attempts to clear his name.
In today's era of multiverses, where several different Spider-Men can interact, the prospect of Connery and Brosnan sharing the screen doesn't sound too outlandish. Compared to some of the more fantastical elements of Die Another Day, it sounds eminently sensible. Lee Tamahori says that this Connery cameo was part of a very different Bond movie to the one that made it into production. It didn't make it much further than Tamahori's initial idea, as the concept of a multi-Bond story was vetoed by producers Michael G. Wilson and Barbara Brocolli.
It's interesting to ponder how Connery's cameo would or wouldn't have fundamentally shifted the course of Bond history. While many people have gravitated to the "codename" theory regarding the franchise, the movies don't really back it up. James Bond marries Tracy and watches her murder when he's played by George Lazenby; he avenges her death when he's played by both Sean Connery and, finally, Roger Moore, whose Bond kills Blofeld after visiting his wife's grave. While Connery's Bond meeting Brosnan's wouldn't necessarily retcon this loose continuity, it would certainly complicate matters further. This is likely what Tamahori was referring to when he said his producers might have felt audiences would be confused by two James Bonds sharing a screen. In the end, it was deemed an anniversary present too far, and the studio went in a different direction with Die Another Day. However, with Daniel Craig's James Bond having been killed in the line of duty and a new 007 in the form of Lashana Lynch, there does now exist the possibility of resurrecting the "codename" theory in a future James Bond movie.