Dahmer, who attained a morbid kind of celebrity status world-wide, with donations of money arriving in his cell from places as far away as London, was attacked while cleaning a prison bathroom. He died later in hospital from head injuries.
The Wisconsin prisons department reported that an unidentified prison inmate was in custody for the attack. It was not known if it was racially motivated - most of Dahmer's 17 victims were black.
The world first came to know of Dahmer in July 1991, when police searching his home in Milwaukee discovered body parts, including a head in a refrigerator.
Dahmer, who worked at a chocolate factory, told police he picked up most of his victims in gay bars and shopping malls and lured them to his home, where he would drug them before killing them. He admitted to committing acts of necrophilia with four corpses and saving the heart of one for eating later.
In court in 1992, Dahmer pleaded guilty to the murders but tried unsuccessfully to claim insanity on the grounds that he was unable to control the urge to commit the crimes. Even after his imprisonment, he said on television that he still felt the same compulsions. Officials at the Columbia Correctional Institute, where Dahmer was held, were forced to end media access to him after demand for interviews became overwhelming.
The case traumatised Milwaukee and shook the city police department, which was accused of racism and negligence in not apprehending Dahmer more quickly. Police had been to his apartment two months before his arrest after receiving a report of a naked young man on the street outside. They allowed the 14-year-old Laotian to remain with Dahmer and it later transpired that Dahmer had tried to lobotomise the boy, drilling a hole into his forehead and filling it with acid.
An investigation will now be opened into why Dahmer was not better protected. In July another inmate attempted to cut his throat but Dahmer escaped unhurt. At that time, authorities said it was an isolated incident and Dahmer was not in danger.