Jennifer Carpenter

Actress born December 7, 1979, best known as Debra Morgan on Dexter, as well as the titular role in The Exorcism of Emily Rose and Angela in Quarantine, the American remake of REC.

Jennifer Carpenter provides examples of the following tropes:

Artistic License Gun Safety: Averted. She was trained in the use of fire-arms by her father(she's from Kentucky), so any scene in Dexter where her character has a gun(which happens fairly frequently, being a cop), she knows what she's doing.
Cast Incest: Was formerly married to Dexter co-star Michael C. Hall. Technically Dexter and Debra aren't blood siblings, but since they grew up as brother and sister, if the two characters did hook up, it would still be extremely squicky.
- After the end of Season 6, it looks like it might be headed this way.
The Cast Showoff: Saved the makers of The Exorcism of Emily Rose a lot of money on special effects when she pointed out she could do all those weird poses herself.
Rubber Woman: See above.
What Beautiful Eyes!: Her big, cat-like eyes are very distinctive.