International Groups:

Bloodline International - Membership spans 12 countries. Otherkin and occult practioners also included.
Temple of the Vampire - Rumoured to have worldwide membership.

National Groups:

The Coven Organization - United States. Otherkin welcome.
National Vampire Association - United States.
Order of the Crimson Tongues - United States.
Vampire Church - United States.

Regional Groups:

CERC Family
House Crimson Blade - Mississippi. Otherkin welcome.
House Eclipse - Washington DC. Otherkin welcome.
House Lilitu - Alabama.
House Scarlet Moon
House Sekhemu - Texas.
House St. Germaine - Louisiana.