License and passport have no first name and MegaZone for a last name.
My SSN Card has 'Mr MegaZone' - when I changed it, back in 2000, the SSA said their computers just could not handle a blank first name. They wanted to put in something like NFN MegaZone, FNU MegaZone, etc. (No First Name, First Name Unknown) I suggested 'Mr' because it tickled me to make the government call me Mister MegaZone. ;-)
Airline tickets are something where I use Mr MegaZone. I have Global Entry/PreCheck, and even though my IDs have no first name, the ticketing systems do NOT like that. So my PreCheck stuff is under Mr MegaZone. I made the mistake if booking once under MZ MegaZone, and even though all my PreCheck info was on there, it didn't work and I got stuck in the normal security line. Lesson learned.
My passport does break other systems sometimes - I go on cruises with my wife and they, of course, base things on your passport. So I usually end up as FNU MegaZone, which leads to hilarity as crew members try to pronounce 'FNU' as a name. Usually once I'm onboard I can get into the system and edit things, but such is life.
First Name: Mr Last Name: MegaZone
based on what you stated? I figure that gov forms would always require a first / last entry.