With her sunny demeanour, the senior year High School student from Colorado in the USA won the hearts of millions watching the action at the London 2012 Aquatics Centre.
But beneath Franklin’s ever-present smile is an incredible drive to win – and a steely nerve that even her more experienced American teammates cite as an inspiration.
Franklin set an Olympic record in London by becoming the fastest-ever woman backstroker over 100m with a time of 2:04.06secs.
As part of the Team USA 4x100m Medley Relay team she put her name to a second World Record and secured another gold, before wining bronze in the 4x200m Relay.
It was quite an achievement for any athlete, let alone one making her Games debut.
Born in Pasadena, California in 1995, legend has it that when Franklin was two years old, she was in the sea with her mother when she began chasing a fish through the water. Whether true or not, she has since said she can’t recall a time when she didn’t love being in the water.
At the age of 13 she entered the US Olympic time trials for the 2008 Beijing Games but failed to make the cut. It was only a matter of time before medals came, however, and in 2010 she had a first taste of international success, with silver in the 200m backstroke and 4x200m Medley Relay at the FINA Short Course World Championships in Dubai.
That achievement won her the 2010 Breakout Performer award at the USA Swimming Foundation Golden Goggles Awards.
One year later, at the age of 16, she took a world long course record in the 200m backstroke at the World Championships in Shanghai, as part of a five-medal haul that included three golds.
The teenager – who continues to refuse endorsements and prize money so she can maintain her amateur status in college – is built for success, with a powerful 6ft 1in frame, size 13 feet, long hands and a 6ft 4in armspan. Her father Dick, a former All-Canadian football player, jokingly refers to her feet as “built-in flippers.”
To date she has won twelve medals in international competitions – seven gold, three silver, and two bronze spanning the 2012 Summer Olympics the FINA World Championships and the short course FINA World Championships.
After her 200m win at the London Games she said: ‘I definitely took it out really fast. It hurt so bad in the last 25 – that’s the part that I love, knowing that I'm pushing myself past the limit. I’ve been dreaming about this moment my whole life.’
No teenage swimmer has ever been more versatile or dominant in the pool, and Franklin is now tipped to emulate Michael Phelps’ record and become the most decorated female Olympic swimmer of all time.
With a potential three more Games in her sights, the women’s record for most overall swimming medals is within reach.
That accolade, held by US swimmers Jenny Thompson, Dara Torres and Natalie Coughlin – Franklin’s favourite athlete – stands at 12 overall medals.
Considering she is still developing her talent as a swimmer, it seems likely, barring injury, that Missy Franklin will over the next decade prove to be an ample successor to Michael Phelps as America’s outstanding swimmer.