Elemental Masters Series (13 books)
There are 13 primary works and 17 total works in the Elemental Masters Series
Elemental Masters is a fantasy series written by Mercedes Lackey, about an Earth where magic exists and focuses on the Elemental Masters, people who have magical control over air, water, fire, or earth. Each elemental master has power over elementals, as well. Each book in the series is loosely based on a fairy tale.