The evil Kris Howard
Kris Howard (Victory Van Tuyl) is the main villainess from "Smells Like Teen Spirit," episode 6.15 of Castle (airdate February 17, 2014). She is a student at Fairfield Preparatory Academy, the alma mater of Richard Castle.
As revealed later on, Kris was part of a Bling Ring-type trio, which was lead by Madison Beaumont and also included their friend, Hillary Cooper. The group broke in to the homes of Fairfield students and stole various items; mainly jewelry--all to fund Madison's shopping habit. At some point, Kris wanted out of their habitual robberies, but Madison threatened to ruin both Kris and Hillary if they backed out. She was also on the receiving end of a prank that had Madison send a video of her being killed by telekinesis; however, Kris decided to use the video as part of her murderous scheme. During a confrontation, the evil Kris bludgeoned Madison to death and placed Madison's blood on her ceiling. She also played the video on her phone while she and Hillary were in a taxi at night, passing the video off as a face time phone call and making it look like what happened on the video actually killed Madison.
Castle and Beckett learned about the video being staged by Lucas Troy, when Lucas revealed everything during his interrogation. After this, they encountered Kris and Hillary at a school dance, and it was at that moment that the stolen valuables were found, as they hid them in their lockers. Castle and Beckett also revealed Kris as Madison's killer, when the former stated that the video was sent to Kris' phone. At that moment, Kris confessed everything, stating that Madison wouldn't let her quit and that Madison would destroy them. After her confession, Kris and Hillary were both arrested--the former for the robberies and for Madison's murder.