They share a foundation in fairy tales, a yellow VW and not much else. While one fairy tale-themed show begins, another is drawing to a close and although they're both set in a fantasy world, they're two very different, hairy mythological beasts.

TV concepts seem to run in cycles, don't they? We've had superheroes ('Heroes', 'No Ordinary Family', 'Misfits'), aliens ('V', 'The Event', 'Falling Skies'), the supernatural ('Being Human', 'True Blood', uh, 'Supernatural', 'Fringe', 'Lost', 'The Vampire Diaries'), dinosaurs ('Primeval', 'Terra Nova') and general bogeymen ('The Walking Dead', 'The River'). Someone gets an idea and the rest of the industry meekly follows.

So what is behind this sudden spate of fairy tale inspired entertainments? In the past year we've had Red Riding Hood and not one, but two varieties of Snow White ('Mirror Mirror' and 'Snow White and the Huntsman'). 'Jack The Giant Killer' arrives in cinemas next year and [Angelina Jolie will star|http://movies.yahoo.com/blogs/movie-talk/angelina-jolie-maleficent-first-photo-165911375.html] as Disney's evil queen Maleficent in a new movie based on the Snow White villain.

Is it our yearning for the simpler times and terrifying stories of childhood? Do we seek to escape into a world of fantasy, posh frocks and pumpkin coaches? Or is it just that TV producers have run out of their own ideas and find it easier to plunder old (and copyright free!) concepts?

'Once Upon A Time' star Ginnifer Goodwin herself said the chance to play dress-ups as an adult played a crucial part in her decision to take on her role in the show.

"As my agent said when we read the script for 'Once Upon a Time': This is my 'Harry Potter'. This is my getting to satisfy the inner-eight-year-old that has been with me for 33 years asking me to play a Disney Princess."

Oddly enough, Goodwin is living out her own fairy tale fantasy by snagging her own Prince Charming, leading man Josh Dallas.

We weren't expecting to enjoy 'Once Upon A Time'. The premise sounded, well, a bit silly really. A raft of fairy tale characters have been exiled from their magical realm by a curse and are trapped in a town called Storybrooke, a picturesque town that doubles as a prison from which they can't escape.

Most of the townspeople can't remember their former lives as fairies, dwarves and royalty, but we get to see their fairy-tale selves through flashbacks to their fabled pasts.

It sounds like a winning formula for a kids show. It shouldn't work as an adult drama, but somehow it does! Its success is certainly in part to the clever team behind 'Lost' who weave mystery with humour to create something that is uniquely entertaining. It's peppered with clever allusions to 'Lost', other TV shows (a florist has the cheeky business name 'Game of Thorns') and its parent studio Disney. In one scene we see Mary Margaret serving out some justice to the animated blue birds who served her animated counterpart so well in the 1937 classic movie Snow White and the Seven Dwarfs.

What also makes the seemingly impossible wholly believable in this fantasy series is the stellar casting. Robert Carlyle has been deservingly nominated for an Emmy award for Outstanding Supporting Actor In A Drama Series for his role as Mr Gold/Rumpelstiltskin, a man trapped between good and evil and magic and reality. 'Once Upon A Time' is worth watching alone for Carlyle's dual performance as the pantomime-ish Rumpy, who appears as a hobgoblin/Steven Tyler hybrid and the melancholic, Machiavellian Mr Gold.

Established actresses Ginnifer Goodwin ('Big Love') and Jennifer Morrison ('House') both work well in their roles, but it is Lana Parilla as the Evil Queen/Mayor Reigna Mills who has become the breakout star of the series.

While 'Once Upon A Time' is set in the world of fantasy, it does touch on modern day themes and at its essence is a drama about disconnected families, loss and reunion.

There are a lot of ladies giving up babies, and the pains of parenting, motherhood, and separation provide an emotional hamster wheel for the main characters to ceaselessy scamper on. Rumpelstiltskin has lost his son, The Evil Queen her father and her lover, and Snow White has lost her father, her true love and her daughter Emma. The domino effect doesn't end there with Emma having lost her parents and her son, Henry; who is one of the few inhabitants aware of the strange curse under which they dwell.

New series 'Grimm' is a different beast altogether - rather than trying to restore a magical kingdom, the aim is to destroy a magical, murderous breed.

'Grimm' is a police procedural drama in which we follow a crime from inception to end. Unlike 'Once Upon A Time', it's set in one world, this one, which makes it all the more frightening, cheap special effects aside.

When Detective Nick Burkhardt's (David Guintoli) terminally ill aunt arrives unexpectedly, she tells him that with her imminent passing, the family biz of slaying fairy tale creatures will pass to him, and that his parents weren't killed in a crash after all, but by these mythological beasts.

Setting aside that shades of Harry Potter-like revelation about Nick's parental demise, Grimm owes its origins more to 'Buffy The Vampire Slayer' than even the tales of the Brothers Grimm. Buffy and Burkhardt are the human guardians appointed to keep their communities safe from supernatural peril, except rather than popping in from a demonic gateway, Grimm's creatures, known as Wesen (German for creature, or essence) have arrived via Germany and the fairy tales they have inspired. There are some 30 odd different creatures to keep track of, all with weird long Germanic names such as spidery spinnetods and rhinoceros-like Dickfellig.

We're only two episodes into 'Grimm' so it's too early to say if it will too grip us in its cryptozoological grasp, but we'll have time to find out. Both series have a 22-episode commitment, which is more than a five-month burden on our attention spans and our MySky memory.

However, 'Once Upon A Time' has an expiry date lingering over its head. We know that eventually Snow White will get her happy ending; the only question is how many seasons it will take.

'Grimm' on the other hand could solider on for seasons with its episodic take on the literary nasties of the Brothers Grimm. There is a wealth of material to work with; The Brothers Grimm produced over 200 fairy tales and there are an untold number of traditional folk tales ready to be plundered from around the globe. Although we'd prefer they ignore the grisly tale of The Mouse, The Bird and The Sausage.

Both series have been ratings successes in the US ('Once Upon A Time' has a slight lead), which suggests escapism, and the more fanciful the better, is what we're seeking from our TV entertainment. While 'Once Upon A Time' and 'Grimm' both share a common source, one is a story of love, family and reconciliation while the other is blood, duty, guts and gore.

Take your pick.

Once Upon A Time airs Thursdays, 8.30pm. The season finale (featuring some big reveals) will screen Thursday 5 July, 8.30pm. Season two debuts in the US in September.

Grimm airs Mondays, 7.30pm on FOUR