Parents have falsely accused teachers of taking photos of girls and manhandling pupils, as social media abuse of school staff soars.
One headteacher revealed lies had been spread on Facebook about him acting inappropriately towards children and he had even been depicted in an image online as the Devil.
Barry Smith, head of the Great Yarmouth Charter Academy, wrote in his blog this week he was also regularly sworn at walking down the street.
'You get used to it after the first three or four occasions,' he said.
Another head at a north Norfolk high school, who did not want to be named, said he had been called a 'Nazi', 'Hitler' and a 'disgrace to humanity' by people online for enforcing a stricter uniform policy.
False accusations had also been spread about him manhandling a year 11 girl.
It comes as teachers face an explosion in online abuse.
Scott Lyons, National Education Union (NEU) spokesman for Norfolk, said teachers who he represented approached him every month about things parents said about them online.
'Parents have always had opinions about teachers and schools but it has now moved away from the playground to social media,' he said.
'I have seen screenshots, predominantly in high schools, where teachers are accused of looking inappropriately at pupils or saying something inappropriate and it has been used by parents on private social media groups with gripes.'
He said a couple of cases each year had got so bad it had been reported to police.
'It is a massive problem and it has really increased in the last two years,' he said.
Parents can be banned from the school and asked to remove the social media post, but Mr Lyons said once a false accusation was made it had a big impact on teachers.
'It affects their mental health and confidence,' he said. 'It is also really hard to teach a pupil knowing the parent is waging a campaign against the teacher.'
Barry Smith faced a backlash from parents when he took over at Great Yarmouth Charter Academy last year and enforced stricter policies for behaviour and uniform.
He wrote on his blog this week: 'Today someone posted an edited picture of me, depicting me as the Devil with a caption: I will make your school days hellish!
'Last week there were lies circulated about me on Facebook saying I take photographs of year 10 girls on my phone and that, on another occasion, I had to be forcibly escorted off a junior school site for photographing children.
'All these accusations are completely without any foundation.'
He added: 'I've been accused of calling kids fat, of being racist, of bullying children, the list goes on. None of it true.'
The school recorded the biggest improvement in GCSE results in Norfolk this summer. But Mr Smith wrote further lies were spread about the school when it was praised.
'How much of this are we expected to endure?' he asked.
A headteacher brought in to transform a north Norfolk high school, who did not wish to be named, reported similar experiences.
'I've been told I shouldn't have children because I shouldn't be allowed to enforce my personality on them,' he said. 'I've been called fat and arrogant and sworn at.'
He said the majority of the abuse took place on social media, and although some of it was from parents, much of its was from people whom he had never met and had never visited the school.
'I don't know where the aggression comes from,' he added. 'The moment you do anything that anybody disagrees with it evokes a level of vitriol.'
The headteacher added that the vast majority of parents liked the school but a minority had been getting increasingly abusive in the last six months.
He has banned some parents from the school and reported the abuse to police.
The school is also now taking legal advice about whether the comments made about staff would be libellous.
'We had 17 children apologise one week for the behaviour of their parents,' he said. 'The children are phenomenal.'
He said four members of staff were considering leaving the school because of the level of abuse.
'They have never experienced abuse likes this before,' he said.
•Backlash
The two headteachers who have spoken out about abuse both ran into a backlash when they were brought in to transform their struggling schools.
Barry Smith's changes at Great Yarmouth Charter Academy sparked a national debate about discipline when he joined in September 2017.
This summer its results leapt from 30pc of pupils getting the equivalent of grades nine to four in English and Maths - the worst performance in Norfolk in 2017 - to 58pc.
Mr Smith said the school had been turned around, with staff who previously had to lock themselves in classrooms to stay safe, now happy and confident.
The arrival of another head at a Norfolk high school, who did not wish to be named, also prompted changes to staff, behaviour and uniform policies.
The head said that had sparked a stream of abusive comments about him, the school and staff on Facebook.
•What can be done?
Union rep Scott Lyons said teachers had got into difficulty by responding on Facebook to the people who had abused them.
'I've had a lot of casework where teachers have got themselves into trouble by trying to respond and challenge (the person abusing them),' he said.
'Teachers really have to risk assess what they put online and not retaliate.'
Cyber bullying has traditionally focused on pupils but Mr Lyons said teachers were also covered by their schools' cyber bullying policy.
Mr Lyons gives sessions to parents and teachers about dealing with online abuse.
'You've got a generation of parents who are used to social media and putting all their gripes on it, so when they have a negative experience of the school they put it online without proper regard for the impact,' he said.
Schools have banned parents from the site and reported it to the police, but according to one head the abuse is getting worse.
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