Making sure that all employees are actually humans. Many companies had a huge problem with this a few years ago when the rolls of employees were populated by several dogs and cats and a few canaries.
So... making sure that paychecks go out to humans, not animals.
Another great responsibility for the HR department is to make sure that everyone in the company knows that they exist and that "HR" stands for "Human Resources." Many people believe in the conspiracy theory promoted by several QAnon supporters that HR stands for "Holy Republicans."