Independent NTV television said the Moscow regional court had found him guilty of killing 19 people. Six more survived his attacks, it said.
"I will be back," Ryakhovsky said to a survivor in the courtroom who had welcomed the sentence. The television said he intended to file an appeal.
Ryakhovsky, 32, thick-necked, heavy-handed and pasty-faced, earned his nickname because he is almost two meters tall and weighs 130 kilograms.
When the trial started in April, the prosecution accused him of killing 19 men and women aged 14 to 78 up to his arrest in April 1993.
The prosecution said Ryakhovsky carried out necrophiliac acts on his victims and stole their belongings.
He confessed to most of the charges, but later changed this to admitting only three murder attempts on elderly women -- despite the fact that he had led investigators to the naked and headless body of a young boy he had killed.
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