Good book series you enjoy

[Tav]

As you can probably tell from the topic title, this thread is about your favorite books, or book series.
For me, two series come to mind;

John Dies At The End, and the Dresden Files.

And yes, this is my thin attempt at finding new book series to read.

[Borg12345]

I've been listening to what's available of the Horus Heresy series on audiobook, A Thousand Sons was amazing. I felt really sorry of them by the end.