.If your boss says that someone has made a complaint about you.Do you have the right to know who the person is

That kinda depends. If he's going to take formal action over it then yes.
no!
yes!!
p.s. skrw the union
In my opinion you should know that way you can defend yourself...
no in case you beat them up, you may ask tho
If you cannot then anyone can take cheap shots @ you for any petty reason.


Answer:
You have no 'right' to know, in terms of a legal right.
Nor do you have the 'right' to know if the matter leads to a disciplinary process or a report on your record.

You DO have the right to a fair process and procedure if disciplinary action were to be initiated as a result of the complaint.
It would probably not be possible for there to be a fair procedure without knowing the nature of the complaint made, and (if relevant) the person who made it.
For example, if you're working in a shop and a customer complained, it's unlikely the name of that customer would need to be disclosed.
It's a slightly different story if it's a supplier or co-worker.

I hope this helps. As with the answer to so many of these types of questions - the answer is: 'it depends'.
No, just the circumstances of the complaint.
I think if it is to lead to disciplinary action, then the person who complained would have to reveal themselves. If the complaint is explained to you, then maybe you will know who it is anyway. In any place of work, disciplinary procedures should be in place to treat such complaints in a fair and professional way. Also, if you are a member of a Trade Union, you should be able to call on them to represent and support you.