Gary Vinter, who is in prison for double murder, stabs a fellow inmate in the eye and damages his brain.

James `Porky' O'Rourke's addiction to violence makes him one of the most feared and dangerous convicts in the UK prison system. At the age of 22, he killed a man by dropping a slab of concrete on his head.

Mother of two Joanne Dennehy lures a man back to her flat and launches a knife attack on him before stabbing two men out walking their dogs. She gets locked behind bars and is one of only three women serving a whole life order in the UK.

Covered in tattoos, his terrifying appearance adds to Jaime Osuna being one of the most feared men in the US prison system. Awaiting trial, he began practising Satanism and attempted to kill a fellow inmate.

Edward Johnson gets sent to prison for the brutal murder of a female friend, but the violence doesn't end there.

James Robertson is one of the most feared men in the US prison system. He murdered his cellmate, attacked a prison employee and doesn't hold back from getting what he wants.