One Name Characters / GILLIGAN!

I think Gilligan must be his first name. I don't know why I'd say that, but just the way in which the name is said, sounds like a first name. You know, if someone is saying a name which is the person's last name, they say it in a sort of military way (do I know what I'm talking about? - probably not!). In any case, I think it's his first name.