Is there a way to have Excel automatically execute code when it is opened?

I hope this sounds like a terribly stupid question, because It seems like it
should have an easy answer.

The reason I ask is because I want to connect the Excel application to an
application object declared in a class module in Personals.xls, such that I
can write code to evaluate the name of every workbook opened in Excel with a
WorkbookOpen event, including the very firstly opened workbook and without
depending on any specific workbook's auto_open macros.

TIA, MVPs.
I really appreciate any help you can offer. :)

-Mike Mertes
Airtron, Tampa Bay