"What an incredibly beautiful evening being invited to sing at the White House for Potus, Flotus & many special Olympic attendees tonight to celebrate these incredibly inspiring men & women," she wrote alongside a photo of her singing while wearing a sparkly purple evening gown. "I see them beyond their obstacles. I hope you can join me." Katy wasn't the only star in attendance, as Stevie Wonder, tennis player Andy Roddick and his wife Brooklyn Decker were also at the dinner. However, Katy got a special introduction from the president, who admitted he was a big fan of her work. "We have just one of my favourite people performing tonight - Katy Perry, We are so grateful to her," he said, according to E! News. "I love Katy Perry, she is just a wonderful person."