The star, who plays David Platt in Corrie, has been urged to contact police by pals after being bombarded with vile and unfounded allegations for weeks from a variety of aliases.
They pour out hateful bile on his social media pages every time he makes a post.
The crackpot – believed to be a woman – has also targeted his two children, ex-lover Lauren Shippey and current partner Hanni Treweek.
But sources say the star, 30, hopes by ignoring the slurs the crank will lose interest.
“The woman is clearly deranged but Jack says he’s just going to leave it,” the source said.
“But there is a worry they could turn up on his doorstep.
“He’s pretty relaxed about it and says he’s not worried about some demented troll.
“He says it will be someone else’s turn soon.
“But a few of his mates aren’t so sure and are worried.”
The pest – who has been plaguing Jack for weeks – attacked a snap he posted of him posing in a pub with ITV worker Hanni.
It was accompanied by a string of vile comments.
Corrie bosses are aware of the campaign and are monitoring the situation.
Both Jack and ITV declined to comment last night.