As of January 2015, there are 35 books in the Dark-Hunter series by Sherrilyn Kenyon. This includes the collection of novellas released in 2014, entitled Dark Bites.
The chronological order for reading is as follows: Fantasy Lover, Dragonswan (found in the In Other Worlds anthology), Night Pleasures, Night Embrace, Phantom Lover (found in the Dark Bites anthology), A Dark-Hunter Christmas (also in Dark Bites), Dance with the Devil, Kiss of the Night, Night Play, Winter Born (Dark Bites), Seize the Night, Unleash the Night, Dark Side of the Moon, A Hard Day's Night Searcher (found in Dark Bites), Until Death We Do Part (Dark Bites anthology), The Dream Hunter, Fear the Darkness (Dark Bites), Devil May Cry, Upon the Midnight Clear, Dream Chaser, Acheron, Where Angels Fear to Tread (Dark Bites), Shadow of the Moon (Dark Bites), One Silent Night, Dream Warrior, Bad Moon Rising, No Mercy, Retribution, The Guardian, Time Untime, Styxx, Dark Bites, Son of No One and then concluding with Dragonbane.
The Dark Bites compendium contains the story House of the Rising Son which is a prequel to Styxx. There is also a young adult series that follows the character Nick as he meets the other characters. The series will continue until it intersects with the book Night Pleasures.