How to handle temp users during external system import

[Ehren E]

We are currently going through the exercise of importing several years of github issues into Jira, which we will use going forward.  We've written the scripts to export and transform the data to something that Jira expects.  The last piece is mapping the existing github users to newly created jira users.  

Our issue is that there are several "users" that are either no longer with our company, generic users used for some legacy purpose and bot users from various services we used.  These users made comments on our project over time and we want to maintain that historical relevance without having to dig back through old github issues.

Do I have any good options to map those users Jira?  Ideally without creating new users or through some temp user functionality?  There are lots of these users and I don't want to pay for them temporarily while we copy data over.  

Thanks for everyone's feedback in advance.