Sometimes you just want a lot of test data injected into Jira and if you do not want to add Jira users manually here is a Python script that will create 1000 users. All users will be added to Jira Software application and 500 of these will also be added to Jira ServiceDesk application.
The script can be executed as is against a Jira running in the Atlassian SDK where the administrator username and password is admin. If you have other credentials just change the BASIC_AUTH variable in the script.
You can use this script for other JIRA instances as well just be careful. I have tested this on Python 2. The script does not use Python libraries like Requests but uses Python built in modules.