The 84-year-old entertainer was known at an Australian TV channel as "the octopus" because of the way he put his hands on women, the first day of his trial London's Southwark Crown Court heard.
Prosecutor Sasha Wass QC said Harris's alleged victims were overawed, saying: "Mr Harris was too famous, too powerful and his reputation made him untouchable."
Ms Wass said Harris was "an immensely talented man" who excelled in art, music and children's entertainment. He painted a picture of the Queen in 2005 to commemorate her 80th birthday, before being appointed a CBE.
It was his fame and reputation that meant he was able to carry out "brazen" sexual assaults, often when other people were present or nearby, she said.
Ms Wass said: "The prosecution does not, for a minute, suggest there is not a good, talented and kind side to Mr Harris. But, concealed behind this charming and amicable children's entertainer, lay a man who exploited the very children who were drawn to him.
"There is a Jekyll and Hyde nature to Rolf Harris and this dark side of Rolf Harris was obviously not apparent to all of the other people he met during the course of his work, and it was not apparent to those who may want to testify to his good character."
The prosecutor said it was "a side of him which is sexually attracted to children and under-age girls" and "a side which gave him the confidence to molest girls knowing they could not object and, even if they did, nobody would believe them".
She said of the claims by a make-up artist from Australia's Channel 4, that his reputation was such he was known as an "octopus because of the way that he would put his hands all over women".
Harris, sitting in the dock wearing a grey suit, white shirt and multi-coloured tie, listened intently to the proceedings.
His wife Alwen and other members of his family were listening in the public gallery. Ms Wass told the court eight alleged victims will give evidence, four of whom are the subject of charges on the indictment, and the others supporting witnesses.
"The chances of so many people making up similar false allegations are just ludicrous," she told jurors.
The alleged victim, who is the subject of seven of the counts, claims she was abused by Harris, first while on holiday in Hawaii when she was 13 and then continuing over 15 years.
Ms Wass said: "You will hear during the course of this case other instances where Mr Harris touched children and women alike in quite brazen circumstances.
"It may be that that was part of the excitement, knowing that he could do that and get away with it."
It is alleged the girl's parents trusted Harris, so did not suspect him.
"Rolf Harris was a pillar of society, a well-respected man and somebody who was well-known for being fond of children," Ms Wass said.
On one occasion, it is alleged, Harris gave the teenager oral sex as another girl slept in the same room. Ms Wass said the alleged victim thought that it was as though the risk of doing this so near to the other girl was exciting him.
The jury was told: "He never treated her as an equal or a human being. He never had a meaningful conversation with her. She felt, as I said to you, that she was his little toy." Eventually, the woman - whose experiences at the hands of Harris, the court heard, led to her becoming an alcoholic told her parents, prompting her father to write a letter to Harris.
In his reply, he confessed to having a sexual relationship with the woman, but denied it started when she was 13. He described being in a state of "self-loathing" and feeling "sickened" for the misery he had caused.
A third woman was on holiday in Malta with her boyfriend when she was 18 when he started to kiss her before he allegedly indecently assaulted her, jurors were told. There are no charges for this alleged matter, but the court heard Harris will deny the claim.
Another woman is to claim she was abused by Harris at an event Cambridge when she was 14 in the 1970s. The star denies 12 indecent assaults between 1968 and 1986.
The trial continues.