You can do what essentially what you're describing with Data Driven Testing. The idea is you read data from a file (e.g. Excel sheet or CSV), in your case user names, and run the tests with each data item. This can be done using scripts or in keyword tests.
Using Keyword Tests for Data-Driven Testing | TestComplete Documentation (smartbear.com)
I have done exactly what you are describing by reading usernames and passwords from an Excel file I created.
This tutorial should help:
Data-Driven Testing With Keyword Tests - Tutorial | TestComplete Documentation (smartbear.com)
