10. Royal athleisure
It seems innocent, but seeing a royal in biker shorts, sneakers and a baggy sweater was quite the shock back in 1995. Little did we know Diana would go on to become a posthumous activewear fashion icon in the 2020s.
9. Oversized tartan
This look is proof you can take the oversized trend too far. Pairing a huge green tartan coat with a comically oversized matching hat wasn't doing Diana any favours in this snap from 1985 - sorry.
8. The white tux
This outfit made waves because it broke royal protocol - after all, princesses are expected to wear evening gowns to important occasions. Diana bucked that tradition in this white tux and while we commend her bravery, it wasn't her best look.
7. The sheer skirt
This particular outrage wasn't Diana's fault at all. During her engagement to Prince Charles, this photo was snapped of young Diana at a kindergarten in 1980, but the lighting made her thin skirt almost see-through, showing off her legs.
6. A satin nightmare
All we can say about the unique look Diana donned in Lisbon in 1987 is that it made a statement. Whether or not that statement was a fashion-forward one... we'll leave that for you to decide.
5. The little blue dress
During her divorce era, Diana became a huge fan of short cocktail dresses - like this blue halter number she wore to a Vanity Fair party in 1995. She looked ravishing, but old-school royal fans weren't impressed with the racy (for the time) outfit.
4. Diana's strapless mishap
It was one of her first major appearances as a royal and she rubbed shoulders with the likes of Grace Kelly, but when Diana wore this strapless black gown in 1981 all hell broke loose. The neckline was deemed far too low for a princess and it didn't help that the strapless sweetheart neckline left plenty of skin on show. We think she looked great though.
3. Met Gala moment
Negligée-style satin slips are back in fashion in 2022, but Diana was rocking the trend way back in 1996, when she attended the MET Gala in this slinky number. It made headlines for looking like lingerie, which simply wouldn't do for a royal lady, but there's no denying she looks phenomenal.
2. Bikini paps
Paparazzi managed to snap this rare shot of Diana in a colourful bikini in 1988 and everyone lost their minds. Seeing a princess in her bathers - especially one who looked as fit as Diana - was practically unheard of in that era and the photos were considered totally outrageous.
1. The revenge dress
And who could forget the moment Diana stepped out in this tiny black number, hours after Prince Charles confessed to having an affair on national TV. She broke all the royal fashion rules and in doing so made it the most outrageous - and iconic - fashion moment in her history. Good for her.