Trammell, who plays Sam Merlotte in the show, explained that he was impressed when he watched the first episode.
"It's going to be the best season yet, and I'm not just saying that," he told On The Red Carpet. "I just saw the first episode... I think we're sort of hitting our strides. The writing is so good this year."
He continued: "There's even more action. And I think the characters' stories are even more rich. So, I mean, it's really, really good this year."
Trammell also suggested that some fans might be surprised with the direction the show takes.
He said: "There's going to be some really, really interesting kind of supernatural, sci-fi element to it this year that's going to be completely unexpected and it's going to be really cool, really cool."
The third season of True Blood begins on Sunday, June 13 on HBO.