No pen name would imply a written product; it’s too refined for the internet. I would say “user name” or “screen name.”

I generally refer to it as a handle. But I am old and have spent some time on the CB.

I’d use “screen name” in most contexts. “Persona” might work, too.

Generally “username.”

Depending on the specific service being discussed it may be more specific, such as “handle” for Twitter (though I rarely use that), or “moniker” if talking about my name/identity used across many services (zants).

Screen name, usually.

Virtual AL

Login name or Username.

I refer to “muppetish” as my username in reference to “the words that I am typing to sign into the forum”, but prefer “handle” when referring to it as my identity.

I say username.

I say “username” too, in most cases.

Screen name.