In 2013 at Cardiff Crown Court, Watkins denied rape but admitted the attempted rape and sexual assault of a child under 13.
He admitted 13 offences, including conspiring to rape a child, three counts of sexual assault involving children, seven involving taking, making or possessing indecent images of children and one of possessing an extreme image involving a sex act on an animal.
Prosecutors had described him as a man corrupted by fame, drugs, and power who had committed crimes “beyond imagination.”
Mr Justice Royce said the case had broken “new ground” and “plunged into new depths of depravity”.
Watkins was also stabbed in prison in 2023. Following that attack, he was taken to hospital with injuries which were not life-threatening.
Rashid Gedel, 25, and Samuel Dodsworth, 43, appeared in court last week charged with his murder, but were not asked to enter pleas.