There are at least two people in the Bible named Jotham. One was the son of Gideon. The other was a king.
The first Jotham was the youngest son of Gideon, who was a judge of Israel. Jotham's brother, Abimelech, tried to seize power by killing all of his own brothers. Jotham escaped and was the sole survivor. Jotham pronounced judgment on Abimelech and the Shechemites by telling a parable of the trees, while standing on Mount Gerizim (Judges 9:7-20). In fear of his life Jotham fled to Beer. Jotham disappears from the Bible, and no more is recorded of him. But the judgment he placed on Abimelech and the Shechemites was fulfilled three years later.
The other Jotham - the king - assumed the throne of Judah when he was 25 years old. He reigned for 16 years, although some of these years might overlap with the reign of his father, Uzziah, while Uzziah was isolated with leprosy.
Jotham's mother was Jerusha, who was the daughter of Zadok. Jotham followed the generally good example of his father. He built the upper gate of the Temple and did extensive rebuilding of the walls on the hill where the Temple was located. He also built cities in the hill country of Judah.
He had a successful war against the Ammonites and received annual tribute from them for three years. King Jotham became powerful because he was careful to follow the path of the Lord (2 Chronicles 27:6). When he died, he was buried in Jerusalem, and his son, Ahaz, became the new king.
The story of King Jotham is found in 2 Kings 15:32-38, and 2 Chronicles, chapter 27.
The name Jotham means "may Yah (a name for God) complete."
Next person in the Bible: Judah, son of Jacob/Israel