In 2010, Tim Curry starred as the roving serial killer nicknamed “The Prince of Darkness,” aka Billy Flynn, who killed for years before tangling with the BAU in a two-part story that begins with the finale of Season 5, “Our Darkest Hour,” and ends in the Season 6 opener, “Longest Night.” When Los Angeles falls into a series of rolling blackouts, Flynn arrives to taunt the grown-up child of two of his past victims. His preferred method is to invade a home at night, often cutting the power, and then torture, rape, and kill the family, leaving any children alive. The character is inspired by the real serial killer Richard Ramirez, who also murdered people during brutal home invasions in Los Angeles.
With “Our Darkest Hour,” the “Criminal Minds” producers were aiming for the scariest finale yet. “Who else can be the creepiest guy without saying a word?” writer and co-executive producer Erica Messer said to TVGuide. “Tim Curry is a dream. [Flynn] kills families, but always leaves one person alive, which is psychological torture for the rest of that person’s life. … He feeds off of making people powerless.” They succeeded: Flynn turns out to be one of the grisliest unsubs of the series, especially in how he endangers and traumatizes children. These are not episodes for the faint of heart because Curry commits to giving the audience nightmares with his chilling performance.