Custom Field that Shows the Name of the Record Creator

1. Navigate to Customization > Lists, Records, & Fields > Transaction Body Fields > New.
2. Enter a name on the Label field.
3. Set Type to Free-Form Text.
4. Uncheck the Store Value field.
5. Mark the applicable fields on the Applies To tab (e.g. Purchase, Sale, etc.).
6. Click Validation & Defaulting tab.
7. Set the Default Value field to: {systemnotes.name}
8. Put a checkmark on the Formula checkbox.
9. Click Save.

Note: This is also applicable to other record types (i.e. entity, item and custom records)