What or who is…
hammelech

Hebrew: הַמֶּ֜לֶךְ

Meaning: the king, the king’s, or prince

This word appears in Jer. 36:26. Most scholars believe this word is a common noun, “the king’s,” and understand that Jerahmeel was King Jehoiakim’s son, a royal prince. The King James Version, however, assumes it is a name.

Jeremiah 36:26 KJV: But the king commanded Jerahmeel the son of Hammelech, and Seraiah the son of Azriel, and Shelemiah the son of Abdeel, to take Baruch the scribe and Jeremiah the prophet: but the Lord hid them.

Jeremiah 36:26 NKJV: And the king commanded Jerahmeel the king’s son, Seraiah the son of Azriel, and Shelemiah the son of Abdeel, to seize Baruch the scribe and Jeremiah the prophet, but the Lord hid them.

Jeremiah 36:26 NASB: And the king commanded Jerahmeel the king’s son, Seraiah the son of Azriel, and Shelemiah the son of Abdeel to seize Baruch the scribe and Jeremiah the prophet, but the LORD hid them.

Jeremiah 36:26 ESV: And the king commanded Jerahmeel the king's son… to seize Baruch the secretary and Jeremiah the prophet, but the Lord hid them.