Which are the best MOOCs on CS or related subjects you've taken?

The online courses world is huge. There are good courses among them and there are bad ones. Above all of them there are some tremendously eye-opening ones too.

Which courses you've taken in the field of CS or related domains that stand out to you?

P.S.: This post is about courses. But if you can't control yourself in mentioning a book, feel free to do so.