Many times, producers have attempted to turn a successful television series into a big blockbuster movie. Sometimes the resulting movie requires too much knowledge of the original series and non-fans are lost (The X-Files: Fight the Future). Sometimes, the film bears little or no relation to the original series and is not strong enough to stand on its own (Starsky and Hutch). Sometimes the connection goes the other way around, and a poor to middling film becomes a hit television series (Stargate, Buffy the Vampire Slayer). But every now and again, a film inspired by a television series stands on its own as a huge success, enriching the television series for its fans and providing a solid couple of hours’ entertainment for non-fans. These are just six of the best.
Dad’s Army (dir. Norman Cohen, 1971)
Dad’s Army was a phenomenally successful British sit-com of the 1970s. Based on co-creator and writer Jimmy 
What makes the film so successful is that, unlike many television-to-film adaptations, it tells a complete story within its own right. The first two series of Dad’s Army were filmed in black and white and much of them were later deleted by the BBC as part of their infamous policy of scrapping old material that also led to the loss of many classic episodes of Doctor Who. The origin of the Walmington-on-Sea platoon, then, was already ripe for a re-telling even after only three series, and much of the film covers the creation of the unit, Captain Mainwaring taking charge, the national blows of the Germans going around the Maginot line and Dunkirk and the platoon’s development as a group. Most of the material is recycled from episodes of the series, but it is put together neatly to create a coherent whole and topped off with a fresh finale. The final sequence in the film gives the platoon a genuine victory and Mainwaring’s best, often over-looked trait – his extreme bravery – comes to the fore.
The television series was always at its best when mixing comedy with serious danger (an episode where Mainwaring and Wilson sit holding an unexploded bomb, an episode where the platoon are trapped in a flooding basement and so on) and the film captures this spirit perfectly. The opening sequence, a pastiche of serious films like The Battle of Britain, is very funny (the Germans look across the English Channel to the cliffs, where they see Godfrey emerging from the men’s toilets) but also effectively reinforces the stark reality they faced – that the Germans were within sight and if they invaded, only Dad’s Army and their farmyard hoes and ancient rifles would stand between Hitler and victory.
Star Trek II: The Wrath of Khan (dir. Nicholas Meyer, 1982).
Some of the Star Trek movies are terrible, but some are truly great. The fight for the prize for the best of all is usually 
considered to be a four-way tussle between Star Trek II: The Wrath of Khan, Star Trek VI: The Undiscovered Country, Star Trek: First Contact (#8) and Star Trek (the new one, 2009).
The Wrath of Khan is probably the best on most counts, but in terms of the transition from television to film, it is certainly the best. While it shares with The Undiscovered Country and First Contact a strong emotional core, the development of the Star Trek universe, moments of hilarity and moments of poetry (usually supplied by other people) it has the edge over these two in terms of standing up as a film in its own right. We learn everything we need to know about Kirk, Spock and McCoy during this film, all necessary back-story is clearly and dramatically explained and the film neither completes (The Undiscovered Country) nor continues (First Contact) a thread from the television series. (It is true that the film forms a sequel of sorts to the episode ‘Space Seed’, which introduces Khan, but that was a one-off story, not an ongoing thread, in the series). The new film stands similarly alone, but loses marks for the pointlessly daft and disgusting-looking beastie on the ice planet.
Of course, the film also features Ricardo Montalban chewing up the scenery, which is always a good thing.
The Naked Gun: From the Files of Police Squad! (dir. David Zucker, 1988)
Quite possibly one of the funniest comedies ever made, The Naked Gun is, of course, ‘from the files of Police Squad!’, 
the relatively short-lived TV series which first introduced Leslie Nielson’s Frank Drebin to the world.
The main thing that makes it so successful is, of course, that it’s simply hilarious. There are so many classic jokes here, from Priscilla Presley’s beaver, to ‘safe sex’, to accidentally assaulting the Queen, to forgetting to take your microphone off while in the toilet. Even the perhaps uncomfortable (with hindsight) presence of OJ Simpson in a supporting role can mostly be shrugged off since he spends his entire screen time being accidentally tortured in various inventive ways.
The other key to The Naked Gun’s success is that, like Dad’s Army, it creates a complete story that takes a feature’s length to tell. In this case, it isn’t an origin story, but Drebin’s actually quite sweet romance with Presley’s Jane Spencer gives the film a structure and a heart. It also features Ricardo Monatalban chewing up the scenery, which is clearly the key to a successful television to film adaptation.
The Addams Family (dir. Barry Sonnenfeld, 1991)
Another hugely successful comedy, the secret to The Addams Family’s success lies chiefly in truly stellar casting. 
The film shares several essential qualities with others on this list; a tightly structured story that stands up in its own right, a lot of heart and a collection of fantastic one-liners. It also benefits from a tonally ideal score from Danny Elfman, great supporting turns from Dana Ivey as Margaret and Paul Womak as the Addams’ unfortunate neighbour, and the most memorable school production of Hamlet you’re likely to see.
No Ricardo Montalban though, unfortunately. We have to make do with Christopher Lloyd instead – but he’s just as good.
Serenity (dir. Joss Whedon, 2005)
The critical (if not commercial) success of Serenity is all the more surprising, given that it exists purely to tie up and 
finish a television series that was cancelled early. However, Serenity provides just the right amount of flashback and back-story to fill in those who haven’t seen the television series, and not too much that it overwhelms the film. Meanwhile, the story of the film feels complete if you only watch the film (perhaps less so if you watch the series as well, and are wondering when Shepherd decided to leave).
It’s not a perfect film and there are problems. Even without the fondness for the main characters that comes with being a fan of the television series, the death of Wash is a bit too abrupt for a space opera (contrast the hyper-tragic, drawn out, sacrificial death of Spock with the supposedly more ‘realistic’ but much less emotionally satisfying sudden taking out of Wash). The film overall has a heavy, dark tone that means those who weren’t fans of the television series but have been persuaded to see it may not be converted by such a bleak story.
However, what the film lacks in scenery chewing from Ricardo Montalban, it makes up for in a truly chilling performance from Chiwetal Ejiofor and at least a couple of characters manage to scrape together something resembling a happy ending. And for fans of the TV series, it provides some much needed answers and closure.
Sex and the City (dir. Michael Patrick King, 2008)
Not the second Sex and the City film, which was thoroughly lambasted by critics and audiences alike, but the first, 
which provides a genuinely satisfying experience and which catered to a desperately under-served market of women over (and, indeed, under) the age of twenty-five.
The first part of this film, all wedding dresses and fancy apartments, is perhaps a little too light, and the second literally a little too dark (the heroine is forced into black outfit after black outfit and even her trademark blonde hair is transformed into brunette) but overall it captures the tone of the TV series perfectly. The story focuses on the friendships between the women, always the most successful aspect of the television show, and provides real emotion in among all the glitz and glamour – there’s barely a dry eye in the house when Miranda calls Carrie in distress at finding herself, once again, alone on New Year’s Eve, and Carrie rushes around in her pyjamas to comfort her.
The biggest flaw in this film is that stories which had been neatly and satisfactorily finished off in the television series have to be opened up again. Would Steve really cheat on Miranda, or Big really run out on Carrie? Haven’t we seen these couples break up and make up enough times already? However, as a film in its own right, the story, structured around a single year and taking artistic advantage of the changing seasons (and fashions) works much better. Important back-story is filled in quickly in the opening credits, but it doesn’t really matter – it’s pretty clear how everyone relates to each other. The film produces a single, well paced, structured story (for the most part – the less said about Samantha’s supposed weight gain, the better). Most importantly, it fulfils the most important remit of a TV to film transition – it provides a couple of hours in the cinema that will entertain fans and non-fans of the original show alike.
– Juliette Harrisson