Madison is a villainess from NCIS episode 4.09, "Twisted Sister."
She was played by Katherine Bailess.
Madison is the captain of a college cheerleading squad, but some time before the events of the episode, she found out about a scathing anti-cheerleader blog posted by Sarah McGee (NCIS Agent Timothy McGee's sister); with Sarah posting the rant due to her lover, Navy Seaman Jeff Petty, breaking up with her and later dating Carolyn (another cheerleader). Furious over the rant, Madison colluded with security guard Samuel Tate in a revenge plot against Sarah. Knowing Sarah's favorite food by heart (cheeseless pizza with pickles and peanut butter), the evil Madison laced Sarah's peanut butter with GHB, a date rape drug, and set her up to be raped by Tate.
Petty arrived at the scene to save Sarah, but he ended up stabbed to death by Tate, with Sarah left to be accused of the murder. Security video discovered by NCIS revealed Madison's role in the set-up of Sarah and the murder of Tate, and it was at the campus that McGee and Tony DiNozzo arrived to confront the villainess, who was slapped twice by Sarah. Madison was handcuffed by DiNozzo, all the while denying killing Petty and putting all of the blame on Tate, only for Tate (who was also arrested) to do the same to Madison.