Is there another expression, apart from what's-his-name (or similar), which is used when somebody is speaking of a person, but doesn't remember the person's name?
I thought Vattelapesca was used in English too, but apparently it is not. I know that in American English Joe Doe, or Joe Six Packs is also used, but I think it is used when a person cannot be identified (for example, a homeless man), or to refer to an ordinary man.
First of all, it's actually John Doe, not Joe Doe, and the female equivalent is Jane Doe.
And no, what's-his-name/what's-her-name is by far the most common option for referring to people whose name you can't remember.
The common alternative is to identify the person without using a name at all:
I saw that girl yesterday, that one who hit you with her car. Remember her?
Well did -- what's his name? -- your cousin -- try using a trowel?
In lieu of what's-his-name, among teenagers you will sometimes hear what's-his-face and in more vulgar terms what's-his-fuck.
Another term you will see is So-and-so, but this is used when the name doesn't matter, not when you've forgotten it.
Johnny told me that he heard from so-and-so that you can just fix that with duck tape, actually.
I've heard Mr. X or Mrs. X used by English-speaking people, and it does not seem to be vulgar. Instead, it resembles numerous positive examples from literature, music, and cinematography.
Wikipedia has a list of placeholder names, but they all look very informal, except, maybe, So-and-So.
You'll sometimes hear something that can be remembered about the person in lieu of their name:
This is Mrs. little Johnny's mum.
Over there is Mr. Jeff Rogers and Mr. Jeff Roger's boss.
(American English) I've heard "So-and-so" as a replacement for a forgotten name pretty often in conversation. In written English, this doesn't get used.
Also, "Mr./Mrs. What's-his/her-face". Less common, but understood and not archaic or anything. Likely a derivative of "What's-his-name".
In certain contexts, one could use "you-know-who", but usually this is when both know the name and wish to avoid speaking the name for some reason.
We tend to give whatever we know about the person as replacements for a name, too, and a more diminutive way could even be "Mr./M(r)s. [attribute]". As an example, if I were talking about a friend of mine who never pays attention in class, I might say, "Hey, Mr. Too-cool-for-school over there just mowed my lawn!". This can be done in a variety of ways, like "Ol' (Old) _____", but the general idea is that people tend to fill in anything they know about the person, like "that guy on the news who fell from space" (Felix Baumgartner), or "which president, the one on the twenty?" (Andrew Jackson) in informal contexts.
