What is the name of the killer in 'The Texas Chain Saw Massacre' (1974)?

What is the name of the killer in the 'Halloween' film series? What is the name of the killer in the 'Friday the 13th' film series? What is the name of the killer in 'A Nightmare on Elm Street'? What is the name of the killer doll in 'Child's Play'? What mask does the killer wear in 'Scream' (1996)? What type of mask does Jason Voorhees famously wear? What is the name of the clown in Stephen King's 'It'? In which state is the fictional town of Derry, from 'It', located?