When I was 10, in Year 5, a girl in the year above who, along with her friends, bullied me relentlessly, and bullied others too. They hated lots of people, but when it came to her party, she invited everyone from Year Three to Year Six, with the exception of me - she invited all the others she picked on and bullied, but not me. She then got her friends to come up to me through the day and ask if I'd had my invite, and when I said no, they'd say "Oh yeah - she doesn't want you there" or "Oh yeah, she said you'd spoil the party if you were there".
At the end of the day I went to the school gates and her Mum was asking if everyone had their invites yet. I said no and she said "Oh yes... sorry, she didn't want you there" in the nastiest way possible.
I didn't want to go to her party, but it was clear that she - and her mum, who hated me because she hated my parents for being a) English and b) on benefits - had decided to hand out invites in that particular way to rub it in my face, and I was heartbroken over it. Had I been invited... or even just not given an invite... I wouldn't have gone, and would probably have been fine, but to have had it rubbed in my face that I'd been purposely not invited - when everyone in the surrounding years of school was - by not only the girl and her friends, but by the parents too - it was awful.
Whenever I had a party, I'd seek out those I wanted to invite and give them the invite personally, rather than getting the teacher to do it/standing in front of the class. When I did have a big birthday party - I think I was 5 - we did invite the whole class. Leaving one or two people out - unless that person has bullied the child - is disgusting.