Natan Melech was the servant to which King - you guessed it - King Josiah - the king that led the religious reforms in the Kingdom of Judah.
This seal marks the first appearance of the name Nathan-Melech outside of the Bible, who helped King Josiah with his religious reforms.
“He removed from the entrance to the temple of the Lord the horses that the kings of Judea had dedicated to the sun. They were in the court near the room of an official named Nathan-Melech. Josiah then burned the chariots dedicated to the sun.” (2 Kings 23:11).
Dr. Yuval Gadot, Dr. Mendel-Geberovich of the IAA, who deciphered the text, points out that the fact that the official is mentioned by his first name alone attests to the fact that he was well-known, and no reference to his family relations was needed.
According to Dr. Mendel-Geberovitch, “The name Nathan-Melech is considered to be rare both in the Bible and as an archaeological finding; in both the title describes a man who is close to the king (the king’s servant and chamberlain) and both date from the same period: the mid-seventh century BCE, the times of King Josiah."