7. He Disintegrated An Ood With His Makeshift TARDIS
In The Doctor's Wife, the Doctor finds himself without a TARDIS. In a weird turn of events, the TARDIS' spirit has entered the body of a woman named Idris, so with no means of transportation, the Doctor is forced to build a brand-new one, using any and all random parts that he can find.
He eventually manages to craft something that actually flies, and with Idris in tow, jets off to save Amy and Rory, who are being hunted by a sinister Ood called Nephew. Just as Nephew is about to catch his victims, the Doctor lands his new TARDIS right on top of him, which materialises Nephew with no chance of escape.
Now, the Doctor didn't mean to land smack-bang where Nephew was stood, but it's still not a pleasant way to go. As the Doctor puts it, the people in the room ended up "breathing" all those disintegrated Ood particles, which basically means that Nephew was ripped apart at a molecular level.
The Doctor is a big fan of the Ood too, and has shown an affinity towards them in the past - even in this episode. This makes it even weirder that he doesn't seem to care that he just murdered one.