It may happen from time to time to stumble upon weird GUID accounts in your logs. They will resemble something like <guid>@00000003-0000-0ff1-ce00-000000000000.
For those of you that haven’t published an app/ set-up a S2S trust relationship, well, never seen this , here is the explanation.
“The audience principal for a SharePoint Add-in is always 00000003-0000-0ff1-ce00-000000000000″
This basically means that whenever you see this, it will have something to do with an internal SharePoint object (audience, app principal etc…)
If it’s a”pseudo user account” like GUID 00000003-0000-0ff1-ce00-000000000000
DO NOT DELETE IT. you will end up in a world of sorrow, pain and errors.