The 10th Doctor has a little visit with Hermione in this great Doctor Who and Harry Potter t-shirt mashup art. It was created by khallion, who had this to say about it.
The episode "The Girl in the Fireplace" might be my all time favorite. And I am a big Potterhead, so it seemed an interesting idea to replace the woman that the Doctor meets in the fireplace, Madame de Pompadour---a strong female character---with another strong female character. By doing so, I wanted to create a new story with a commentary of my vision for these characters and illustrate a natural way in their stories for them to interact that would alter their outcomes in a meaningful manner.
The shirt can be purchased at Teefury!