FBI Agent Diana Barrigan

Diana Barrigan is Peter Burke's sharp, unflappable partner at the FBI, working the white-collar crime unit with a cool professionalism that never quite masks her dry wit. She's skeptical of Neal Caffrey's charm from the start, more interested in results than banter, and clearly one of the most competent people in any room she enters.

Thomason plays Diana as the show's steady counterweight to Neal's roguish improvisation—she doesn't fall for the smile, and that resistance gives every scene with him a little friction worth watching. The writing trusts her competence rather than overexplaining it, and Thomason's clipped delivery makes her restraint feel like its own kind of charisma.