Series 7's The Rings of Akhaten contains many good elements, such as the Eleventh Doctor's long and much loved speech to the planet-sized parasite god. But the story also contains a truly dreadful enemy for the Doctor. No, it's not the Vigil or even the mummified alarm clock in the glass case. It's the aforementioned planet-sized parasite god, the one the locals call "Grandfather". Huge monsters the size of planets or stars have been done before in science fiction generally and in Doctor Who specifically (in Series 3's 42, for a start), but it's not the scale of the villain that's the problem. It's the crudely drawn smiley face. As if the absurd face on the gas giant alien wasn't bad enough, the creature also can't communicate. Most stories featuring a vast intelligence facing off against the Doctor provide a way for the villain to somehow interact with the hero - by possessing another character, usually. But Grandfather can't manage even that, forcing the Doctor to keep up both sides of the conversation all by himself. Yes, it results in a beautifully worded soliloquy, but it also feels a lot like the Doctor is trying to bore the "god" to death, and he's running the risk of subjecting the audience to the same fate, too.