The tag alias #76741 herbert_the_pervert -> john_herbert_(family_guy) is pending approval.

Reason: I believe Herbert's first name is revealed officially as "John" in "Valentine's Day in Quahog".

Canonically, that is his first name. However, I think the opposite direction in aliasing would work better since his first name is lesser known, much like Ozzy Osbourne’s stage name is more commonly known than his real name John Osbourne.

I personally think it's better to use the common name for fictional characters. I don't know much about Family Guy, but if the full name only came up in one episode and no one ever uses it otherwise, it's really more of a trivia fact rather than a name we should actually be using. If it's actually the name that appears in the credits or in marketing materials, I think that name could be given more consideration.

I think most people would be confused if shaggy_rogers was norville_rogers, or if jerry_mouse was gerald_jinx_mouse. Whether the full name is canon or not also becomes a problem. For example, inspector_gadget is called john_brown in the live action movie, but that name isn't used in the cartoon or other media. I don't know much about Family Guy, but I'm pretty sure the episodes don't exactly follow a consistent continuity and information is frequently retconned - if it's only appeared in one single episode it doesn't seem too unlikely that another future episode could give him an entirely different first name.

I think this is a case in that the vastly overwhelmingly majority of people only know him by the nickname

faucet said:
I personally think it's better to use the common name for fictional characters. I don't know much about Family Guy, but if the full name only came up in one episode and no one ever uses it otherwise, it's really more of a trivia fact rather than a name we should actually be using. If it's actually the name that appears in the credits or in marketing materials, I think that name could be given more consideration.

I think most people would be confused if shaggy_rogers was norville_rogers, or if jerry_mouse was gerald_jinx_mouse. Whether the full name is canon or not also becomes a problem. For example, inspector_gadget is called john_brown in the live action movie, but that name isn't used in the cartoon or other media. I don't know much about Family Guy, but I'm pretty sure the episodes don't exactly follow a consistent continuity and information is frequently retconned - if it's only appeared in one single episode it doesn't seem too unlikely that another future episode could give him an entirely different first name.

I used to watch all of the seasons repeatedly as an adolescent, I can semi-confidently say that (at least for the first 8 or 10 seasons) everyone just calls him Herbert

it seems like it'd be a very odd choice to move a character away from a name that requires no disambiguator over to one that does.

Either use herbert_(family_guy) or john_herbert, you don't need a suffix if the full name is unique and hasn't seen any use by any other character yet.
However, seeing that the nickname does not seem to have been used in any official media, one of the above "proper" names should be used rather than the nickname fans gave him.