Joe Bloggs

In English, there are several ways to refer to an unspecified or average person:

Joe Bloggs (John Doe in US); average Joe; so-and-so (be careful - a so-and-so is also derogatory); somebody or other; Tom, dick and Harry; what's-his/her-name.

E.g.

If Joe Bloggs wants to buy Marijuana, then that's his or her choice - Si fulanito quiere comprar  marihuana, pues es su elección (unspecified average person)

Elon Musk isn't your average Joe - Elon musk no es un tío normal y corriente 

She's always complaining about something. Either her boss is harassing her or so-and-so is talking about her behind her back -Siempre se está quejando de algo. Que si su jefe la está acosando o fulano está hablando a sus espaldas (specific unnamed people)

Don't listen to John. He's a lying so-and-so - No le hagas caso a John. Es un hijo de su madre

Nowadays, no matter what you say you'll offend someone or other - Hoy en día, digas lo que digas ofenderás a alguien

We can't have every Tom, Dick and Harry turning up asking for money - No podemos permitir que todo quisqui se presente pidiendo dinero

I bumped into what's-his-name from the butcher's last night- Anoche me topé con el de la carnicería (Pepe, Paco o como se llame)