so-and-so; someone (unspecified)
Used to refer to an unspecified person or people, similar to 'so-and-so' or 'someone or other'. Often used when the speaker does not know or does not want to specify the name.
誰々が来るって聞いたけど、名前は忘れた。
I heard that so-and-so is coming, but I forgot the name.
who?; which people?
Used as a question word asking for the identity of multiple people, similar to 'who (plural)?' or 'which people?'. Less common than the singular 誰.
パーティーには誰々が来るの？
Who (all) is coming to the party?
誰々が賛成し
誰々さんから電話があったよ。
There was a call from a Mr. So-and-so.
Please tell me which people agreed.
Kana spelling is common in informal writing and when the kanji is not needed.
Alternate spelling without the iteration mark; less common but still used.
Reduplication of 誰 (だれ, 'who'), with the second character often replaced by the iteration mark 々.