The James Bond franchise is the longest-running continuous series in film history and, behind "Harry Potter," the second most successful franchise in cinema history (and by the time "Skyfall" finishes up, will likely take the crown back again). And one of the most impressive things about that achivement, and I say this is as a British writer raised on Bond movies on rainy Bank Holiday afternoons, is how many of the films are simply not very good.

There are scattered highlights, to be certain -- much of the Connery era, a few Roger Moores, a Brosnan, "Casino Royale." But for every genuinely classic entry, there are probably two mediocre (or worse) films. Some of them might have scattered things to enjoy in them, but there's a few that can't even claim that much. With the latest film, "Skyfall," hitting theaters this week (and proving to be one of the better films in the series), we're continuing Bond week (read our take on the franchise's best villains and action sequences) by picking out our five least favorite 007 adventures. Disagree? Defend your favorite, or attack another, in the comments section below.

Diamonds Are Forever
"Diamonds Are Forever" (1971)
Sean Connery stepped away from playing 007 after "You Only Live Twice" in 1967, with replacement George Lazenby stepping in for 1969's "On Her Majesty's Secret Service." But Lazenby, after clashing with producers, bailed on the franchise after only one entry, and while producers considered names as varied as Michael Gambon and Adam West, "Psycho" actor John Gavin won the role, only for United Artists to decide they wanted Connery to return, offering him a record salary and funding for two projects of his choice for the trouble. Even so, Connery may wish he hadn't bothered, because "Diamonds Are Forever" is easily the actor's worst of his six outings in Bond's tuxedo. Revolving around Blofeld (Charles Gray)'s scheme to use smuggled South African diamonds to power a laser satellite with which he can menace the globe, the film's choice of locations -- South Africa, Amsterdam, Las Vegas, Baja California -- feel significantly less glamorous and sleazier then in your average entry, while Gray is easily the least effective of the Blofelds. Indeed, the cast in general, from Jill St. John's stilted love interest to Bruce Glover and Putter Smith as gay assassins Mr. Wint and Mr. Kidd, are mostly flat. The plot is convoluted and sees the encroachment into silliness that the earlier Connery entries mostly did without, and the actor himself feels disinterested. Even director Guy Hamilton, whose "Goldfinger" was one of the peaks of Connery's five prior films, seems to be phoning it in, with a pretty uninspiring selection of setpieces. It's not the worst of these five films, but it's still a pretty dismal (official) finale for the seminal James Bond, who probably wishes he'd left it at five (Connery would return one more time for unofficial entry "Never Say Never Again," which is pretty mediocre, but just decent enough to stay off the bottom five).

"Moonraker" (1979)
Every generation in theory has a particular fondness for the Bond that they grew up with, so Roger Moore has his defenders out there, but as far as we're concerned, it would have been fairly easy to pick out five terrible Bond movies from his time in the role. Only "The Spy Who Loved Me" is anything like a success, while the other films have occasionally strong set pieces or other pleasures to be found, but mostly suffer from weak scripts, haphazard tone and an ever-aging Moore, who was close to 60 by the time he departed the role. But the very nadir has to be "Moonraker," an unconvincing attempt to cash in on the success of "Star Wars" two years previously. This time out, 007 is out to stop the most ludicrous plot in a series full of ludicrous plots: villain Hugo Drax (Michael Lonsdale)'s plan to destroy the earth, and then repopulate it with the perfect-looking inhabitants of his space station city. One certainly can't fault the film's ambition: it trots the globe from Africa and Venice to Rio and the aforementioned space station. But the result is something frantic and overstuffed, with wall-to-wall action but no sequences that really impress, bar perhaps the opening sky-diving stunt (which sets up the ridiculous tone by having returning fan-favorite henchman survive a plunge from 30,000 feet by landing in a circus tent). The sure touch that Lewis Gilbert ("Alfie") showed in "The Spy Who Loved Me" is nowhere to be found here, the tone feeling closer to parody than straightforward action-adventure, and by the time you reach the space station, you're no longer watching a Bond film, you're watching a poorly-conceived "Our Man Flint" sequel. Still, the space gamble worked out financially: the film took over $200 million worldwide, and it stood as the series' highest-grossing entry until "Goldeneye" sixteen years later.