Another possibility: The Talon series by Julie Kagawa.
The series revolves around dragons with the ability to disguise themselves as humans and an order of warriors sworn to eradicate them. The dragons of TALON and the Order of St. George have been at war with each other for centuries. The fabled creatures, whose existence is unknown by the general public, are determined to rule the world. Their foes, a legendary society of dragon slayers, are equally bent on driving the fabled beasts into extinction. However, when a young dragon and a hardened slayer unknowingly befriend each other, it has severe repercussions for both organizations.
Currently the titles in this series are: Talon, Rogue, Soldier, Legion, Inferno.