Intentionally unspecified
Your Question asks about other passages. Here is a strikingly similar one:
Ezekiel 34:2 (NASB)
“Son of man, prophesy against the shepherds of Israel. Prophesy and say to those shepherds, ‘This is what the Lord God says: “Woe, shepherds of Israel who have been feeding themselves! Should the shepherds not feed the flock?
Juxtaposing similar passages can help us understand both.
Interestingly, both are to "leaders" or "shepherds" (similar concept, different words from different authors). And, both give a dissent toward these leaders. This is a reproof against "the man".
With that in mind, those leaders probably knew who they were. That may have been the important part when Micah was originally written. We're supposed to be flies on the wall to watch Micah (and Ezekiel) show us all how God reproves a leader.
And, that makes sense enough to understand why Jesus gives a similar public rebuke to Herod, who certainly fell into the same category addressed by Micah and Ezekiel:
Luke 13:32 (NASB)
And He said to them, “Go and tell that fox, ‘Behold, I am casting out demons and performing healings today and tomorrow, and on the third day I reach My goal.’
That may be all the information we are supposed to get about "who"—someone like Herod.
In Hermeneutics, we always want to ask: To what level can my questions be answered? How much vagueness will the "right" answer leave me with?
Sometimes language is intentionally vague. It seems that both Ezekiel and Micah weren't very concerned about providing a specific answer to your question because they may not have had a specific person in mind themselves. At least from how the text reads, it seems that's what we're left to think.