The actress has been with the vampire drama since season one and plays Tara's mother, Lettie Mae Thornton.

HBO's True Blood has promoted one of its longest-running original players to series regular.

Adina Porter, who plays Tara's mother, Lettie Mae Thornton, will be a regular part of the vampire drama's seventh and final season.

The actress, who also has appeared as Kendra James for two seasons of HBO's Aaron Sorkin drama The Newsroom, had been billed as a special guest star on True Blood.

PHOTOS: 'True Blood's' 10 Bloodiest Deaths

In addition to the two dramas, Porter has had roles in HBO films including Gia and Lackawanna Blues. Her credits also include Prison Break, NYPD Blue, Law & Order, Saving Grace and American Dreams. Most recently, she guest-starred on Grey's Anatomy, American Horror Story, Glee, The Vampire Diaries and House, among others.

She's repped by TalentWorks and Bamboo Management.

Porter joins previously announced new series regulars Bailey Noble (Adilyn Bellefleur), Amelia Rose Blaire (Willa Burrell), Luke Grimes (James) and Karolina Wydra (Violet).

The final 10-episode season of True Blood returns in 2014.

E-mail: Lesley.Goldberg@THR.com

Twitter: @Snoodit