Billy Flynn (Criminal Minds)

Billy Flynn, also known as the Prince of Darkness, is a prolific serial killer-turned-spree killer and rapist (later abductor) in the series Criminal Minds, in which he appeared as the main antagonist in the season five finale Our Darkest Hour and the season six premiere The Longest Night.

He is portrayed by legendary actor Tim Curry who also played Frank-N-Furter, Wadsworth, Lord of Darkness, Pennywise The Clown, Hexxus, Mr. Hector, Cardinal Richelieu, Farley Claymore, Long John Silver, King Chicken, Maestro Forte, Professor Calamitous and Von Talon.

Background
Billy Flynn grew up with prostitute and drug addicted mother Nora in the suburbs of South California. At age of 13 in 1968 he shot her dead along with a client and was arrested, although got released in 1973 once he turned 18 due to him being a juvenile offender. In 1984 he began to commit burglaries in California, which just so happened to coincide with the first known murders of serial killer Richard Ramirez.

Billy went from robberies to raping and murdering the resident of the houses, although would leave victims alive. In one of these incidents the left a boy named Matt Spicer and his-infant sister Kristin alive after killing their parents. Somehow acquiring an RV and left the state to continue his burglaries, rapes and murders elsewhere, again leaving a surviving victim behind. In this time he took to heavy smoking and using meth.

Season 5
Billy returned to in California in 2010 and continued his raping and killing spree, which was a way to taunt his surviving victim Matt who was now a police detective and haw daughter of his own. Billy targets his grown up sister and daughter and ties them up and beats Kristin badly. The BAU (Behavioral Analysis Unit) come to realise about connect to Matt and that Kristin and his daughter Ellie are the next targets. Agent Derek Morgan arrives at the address with Matt but they are ambushed by Billy, who handcuffs Morgan. Billy then shoots Matt and kidnaps Ellie.

Season 6
Billy begins to try and make Ellie take part in his robberies and killings. However during an attempted robbery where Billy prepares to rape a victim, he discovers that Ellie has allowed one of the children to escape and get help. Billy manages to escape with Ellie before an angry mob arrive to catch him. On the radio an agent JJ makes an appeal to Billy reaveling she knew what his mother had done, although condenms him for his actions. Billy decides to let Ellie go and later breaks into a couples' home and bound and gags them. He is concerned by Morgan in the bedroom, and seemingly for the first time opens up about killing his mother and asks Morgan if he believes in heaven. Billy points his gun to the couple, which results in Morgan shooting him dead.

Despite being taken down, Billy had left Ellie fatherless as Matt died of his bullet wound, and also his sister Kristin died in hospital due to the injuries Billy inflicted on her. Ellie was later sent to live with her mom.

TRIVIA

 * Billy appears to be based off real-life serial killer Richard Ramirez, which is mentioned in the show itself.