Gen 41:46 Joseph was thirty years old when he entered the service of Pharaoh king of Egypt. And Joseph went out from Pharaoh's presence and traveled throughout Egypt.

1Sa 17:33 & 34. Saul replied, "You are not able to go out against this Philistine and fight him; you are only a boy, and he has been a fighting man from his youth." But David said to Saul, "Your servant has been keeping his father's sheep. When a lion or a bear came and carried off a sheep from the flock,
2Sa 5:4 David was thirty years old when he became king, and he reigned forty years.

2Ch 24:1 Joash was seven years old when he became king, and he reigned in Jerusalem forty years. His mother's name was Zibiah; she was from Beersheba.

2Ch 34:1 Josiah was eight years old when he became king, and he reigned in Jerusalem thirty-one years.
2Ch 34:3 In the eighth year of his (Josiah ) reign, while he was still young, he began to seek the God of his father David. In his twelfth year he began to purge Judah and Jerusalem of high places, Asherah poles, carved idols and cast images.

Luke 3:23 Jesus Christ himself was about thirty years old when he began his ministry. He was the son, so it was thought, of Joseph, the son of Heli,