One method that can be used to show the display name for fields that use the loginid as the link to the user.
1. Open the target business object 2. Create a Unicode Text field long enough to hold the display name (CreatedByDisplayName) 3. Go into 'CreatedBy' and mark the field as validated. 4. You will want to use a picklist that returns the loginId of the target object, like Employee. If the display field value is configured for 'Display Name' then CreatedBy will show the DisplayName and not the loginid. "LoginID of ProfileEmployee used in CI.Database" is a good example to use as it only uses the loginid of employee. 5. Add an editing rule that populates CreatedByDisplayName with $([OtherObject]DisplayName) when CreatedBy changes. 6. After saving, when you create a new incident or the field is changed, the CreatedByDisplayName is automatically updated with the display name based on the loginid.