To be hesitant to invite my sons bully?

Not at this age...they are so easily distracted. If invites were handed out at the end of the day then it really wouldn't be a talking point on the playground. At this age they are more interested in running round.. especially boys.
If the birthday boy keeps quiet then it will soon be forgotten. Maybe it would come up again after the party if it's a stand out party but otherwise they will have all moved on to the next party.

Anyway, if it's not all the boys who are going then I don't think it's a problem and I would find it weird if the mum confronted you about her son not being invited. It's pretty normal for parties to be a smaller group and not the whole class (the on MN I know whole class parties seem to be common, so maybe it depends where you live).

Absolutely don’t invite him. Why should continued threats and bullying other boys to rip up their invites get him invited? Time he learned that if you’re friends with people you get invited, if you hit them you don’t. You have limited numbers… what if other children then beg to go?

OP's son is also the same age and doesn't deserve to be worrying over this boy hitting him at his own birthday party. Why should this other boy come before her own son?

Dude, they’re 6. I’m not going to write off a 6 year olds.

Both my children decide on their own guest lists for their parties. They know who their friends are and who they actually like playing with at school far better than parents who aren’t their to observe this daily.

I wouldn’t expect my child to invite anybody who made them feel uncomfortable or who has a track record of regularly hurting them ir others, no.

Kid chat about it in the playground. Doesn’t matter how you invite them, you can’t silence them from discussing it. The birthday child themselves often talks about it a lot too.

Rather disgusting how many posters would force their child to be around their attacker. Would all those posters invite a man who physically attacked them multiple times to their own parties?

I wouldn’t invite him. What if he hurts your child during the party? He may be young, but if you’re not nice to other kids, they won’t want you at their party. Kids always talk about parties at school and most parents have a few experiences of their child coming home upset as kids are talking about a party they are invited to, and they aren’t. It’s just part of life when you’re a kid. The other kids may be talking about it too, but you can’t invite them all. There’s no way i’d invite him after he physically hurt my child.

He’s 5 not 25. Is there a tiny glimmer among all the mumsnet hate for a small child that this might actually be an opportunity to bring them together in a positive way and get to the root of why they don’t get along? God forbid they might actually even become friends.

Sorry but I don't understand how much they are talking about this party.
It's generally known not everyone will get to go to a party. At work teachers will hand out invites as discreetly as possible at the end of the day. Usually these are put into bags to avoid upset on the playground. How did you give out the invites? Were kids opening them in front of everyone? Is it really such a talking point?
I would keep quiet and make sure your own child doesn't mention it.

This.
Frankly, who gives a shit if the bully is sad about not being invited? OPs DS has been sad about being punched and picked on for months. It's a lesson to be learned. Rather it start being learned now than when he's punching people to get his own way in secondary school.

The boy fucked around and found out: if you're mean to somebody, you don't get to join in the fun things that they are doing. It's a very basic life lesson and perfectly appropriate for a 5 year old to be learning it.

I'll be mad at you if you cave and invite him, OP!

This. Plus, threads on here saying my child hasn't been invited to a party get the reply 'tell them no one has a right to expect an invite'. Why is the opposite true if the child is a bully?

I think that 6 year olds don’t really always have full control of their emotions and probably don’t have a full concept of what ‘bullying’ means.
I think being invited to a party might help a child feel wanted and not act out. Or he might come to the party and be a nob 🤷‍♀️. Either way, I’m probably not going to write off a 6 year old as a bully. Given OP isn’t inviting the whole class, she can get away with inviting who her son wants there. Personally, I would use it as an opportunity.

Why? Isn't it the bully's mums problem? There is no way any decent mother would put their sons happiness aside on their birthday and ignore their wishes not to invite the school bully just to satisfy their self indulgent (im such a kind person at my sons expense) ways

The birthday party should be focused on the birthday boy having fun and enjoying his day and not about helping another boy who may just spoil his day anyway once he's got his own way.

the party is to make your son happy on his birthday. Don’t invite the bully. You’re under no obligation to. Help your son by giving him a pre-planned response to say if the bully asks your DS if he can come. Something like “my mum says I can’t invite everyone, and all the spaces are gone” should do the job.

That's not the OPs problem, it's not her job to parent the other child.

Do you mean that 6 year old bullies are cured by party invites or the opposite?

Absolutely, I’m not saying he should be doing it. I’m saying young enough to be manipulated by a soft play party 😂.
He may well be acting out because he thinks he hasn’t got friends - this could help 🤷‍♀️

Right. Then I revert to my first answer - it’s fine.

Yes it is.

Old enough to understand that if you hit someone or kick someone then they aren't going to want you at their party.

They’re 6 don’t forget

No, but being left out could make it worse.