Lords of the Underworld by Gena Showalter

1. The Darkest Fire in the anthology Into the Dark
2. The Darkest Night
3. The Darkest Kiss
4. The Darkest Pleasure
5. The Darkest Prison in the anthology Into the Dark
6. The Darkest Whisper
7. The Darkest Angel in the anthology Heart of Darkness
8. The Darkest Passion
9. The Darkest Lie
10. The Darkest Secret
11. The Darkest Surrender
12. The Darkest Seduction
13. The Darkest Craving (due out in September 2013)

Angels of the Dark spin-off
1. Wicked Nights (events after The Darkest Seduction)
2. Beauty Awakened (events after Wicked Nights) due out February 26, 2013

My thoughts on the series:
I really loved this series and all the characters. You have a cast of Demons, a search for Pandora's Box, Angels, Hunters, Harpies, Gods and a Minor Goddess (but don't tell Anya I said that, lol). All in all a great series well worth reading!