In 2003, Jennifer Telfer the creator of the Pillow Pet (“It’s a pillow, it’s a pet, it’s a Pillow Pet!”) lived with her husband and two sons when she noticed that her eldest had flattened one of his toys by sleeping on it.

She decided to create a range of furry animal pillows with Velcro straps that allowed them to be folded in half into stand-up toys or opened into a flat cushion that could be slept on.

Telfer began selling the toys via a mall kiosk, where they soon sold out. She realised the potential and began marketing them via shops where they exploded in popularity. The company made a reported $300 million (£179.5 million) in sales by the end of 2010.

Her business is well-known for its charitable giving, including many donations to the Family Reach Foundation that helps families of children with cancer.

No one could call Amazon a simple idea now; it’s the world’s largest online retailer selling everything from DVDs to food and toys to cosmetics.

But it certainly started out as a relatively simple idea; the founder Jeff Bezos planned to sell books online. As he wasn’t limited by size like a physical bookshop is, he could retail thousands and thousands of titles.

It was a simple enough premise but one with ambition; he had read that internet commerce was set for growth of around 2,300% and decided to get a slice of the action.

Within two months his new business (founded in his garage) had sold to every US state and across 45 countries. According to Forbes, Bezos is now worth $29 billion (£17.3 billion).

Our next entrepreneur is in a league of her own; she’s the world’s youngest self-made female billionaire with an estimated net worth of $1 billion (£600 million), according to Forbes.

Her idea was as simple as it was brilliant; she liked the way that tights smoothed her silhouette but she didn’t like having unsightly tights fabric poking out of her open-toe sandals. So she started cutting the feet off but found the fabric would roll up.

Sinking her entire savings of $5,000 into finding a solution, Blakely created the slimming undergarment known today as Spanx. Simple and oh-so profitable.

Trevor Baylis, OBE, has been named one of the UK’s 50 greatest inventors and is the mighty mind behind the wind-up radio.

Inspiration struck while watching a programme about the spread of AIDS in Africa, with the conclusion that education via radio broadcasts was the best way to halt the spread of the illness. Before the programme even finished Baylis was in his workshop creating the prototype of a radio that then went on to sell in the millions.

Sadly for Baylis, he made hardly a penny from his radio, despite worldwide sales. A company he went into business with were able to slightly tweak the design and so claim it as their own. He recently revealed he is being forced to sell his home as he’s “totally broke”.

So simple, so clever, so profitable. Rob Law is the inventor of the Trunki, a ride-on children’s suitcase that allows parents to pull their youngsters along at the airport.

It’s been a massive hit with both children and adults, selling two million by the end of 2013 and turning over a reported £7 million a year.

One group who didn’t appreciate the idea were the Dragons’ Den investors, who rejected his request for £100,000 of funding when he appeared on the show in 2006. They have admitted that this may have been a mistake…

In the 1970s Gary Dahl was a Californian advertising exec with a genius marketing ability. After listening to his friends complaining about their pets, he decided to market a ‘pet rock’.

The pet came in a travel box and had a funny instruction booklet. It soon became a major fad and, although it lasted just a few months, it made creator Dahl a millionaire.

He said he had created the ideal pet; he’d certainly invented an ideal money-spinner.

Flappy Bird was a simple game, hardly a complex foray into character development and animation. It featured 2D retro graphics and the player had to direct a flying bird between sets of pipes. It was massively, massively successful but so simple that the creator Dong Nguyen developed it in less than three days.

In an interview with The Verge Nguyen claimed that the game was earning around $50,000 (£30,000) a day.

However, the Vietnam-based inventor then withdrew the game from the various app stores, giving very little reason and simply stating: “I cannot take this anymore.”

Presumably he can handle more financial success as he recently revealed there are three more games in the pipeline.