Wayne Nelson Corliss, whose 2008 arrest was the culmination of an international manhunt, had admitted traveling to Thailand three times between 2000 and 2002 to have sex with at least two boys, ages 6 and 9.
He pleaded guilty last October to five counts that included distribution and possession of child pornography and traveling to foreign countries to engage in illegal sexual activity.
"You have acted beyond the bounds of human decency," U.S. District Judge Joseph A. Greenaway told Corliss on Monday.
The bearded, white-haired Corliss, who is 61 and used the stage name Casey Wayne, was described by people who knew him as witty and friendly and "the best Santa Claus anyone has ever seen." He also worked as an entertainer at corporate parties, art fairs and bar mitzvahs, where his activities sometimes included painting children's faces.
That image clashed with the one presented in court Monday, in which Assistant U.S. Attorney Lee Vartan called Corliss "an irredeemable sexual predator" who bragged on the Internet about fondling young boys while dressed as Santa.
Corliss, who had spoken sparingly in a handful of previous court hearings, pleaded with Greenaway for "a fair sentence, not a death sentence."
While acknowledging his crimes, he claimed that Internet chat postings in which he bragged about abusing other boys as young as 4 were the equivalent of playing a role and did not reflect his true personality.
"I'm not that person," he said. "I'm not that monster."
Corliss' trips allegedly were arranged by John Wrenshall, a Canada native who immigrated to Thailand and has been charged in an 18-count federal indictment. Two Alabama men who accompanied Corliss, Mitchell Jackson and Burgess Lee Burgess, have already pleaded guilty and were sentenced to 6 1/2 years in prison.
Corliss could have received a maximum prison sentence of more than 27 years under federal sentencing guidelines, but the government requested about 19 1/2 years because Corliss' cooperation aided in the cases against Wrenshall, Jackson and Burgess.
Without that constraint, Greenaway told Corliss Monday, he would "not have hesitated" to give him the full sentence. He characterized the case as the most disturbing he has come across in 25 years in the criminal justice system.
"I cannot think of something more heinous," he said. "These children are going to have to live with this for eternity, when their memory should be of a joyful, carefree time."
Corliss' arrest in May 2008 came two days after Interpol took the rare step of asking for the public's help in identifying a man shown in pornographic images. Hundreds of leads flooded in the first day, and eventually led to Corliss' arrest at his Union City home in northern New Jersey.
Vartan, the prosecutor, said investigators believe more people were involved in the ring and that the investigation was continuing.