Who was Othniel?
Othniel was a hero in Israel, son of Kenaz, Caleb's younger brother. He conquered Kiriath-sepher, later known as Debir, in the territory of Judah in the days of Joshua, and was given the daughter of Caleb, Achsah, to wife as a reward (Josh 15:17, parallel found in Jdg 1:13).
He later smote Cushan-rishathaim, king of Mesopotamia, whom the children of Israel had served 8 years, and thus not only saved the Israelites, but by reviving national sentiment among them (compare Ant, V, iv, 3), and reestablishing government, became the first of those hero-rulers known as "judges."
The effects of his victory lasted an entire generation (40 years, Jdg 3:9-11). He had a son named Hathath (1 Ch 4:13) and probably another named Meonothai (compare recensio Luciana of Septuagint, at the place). In the days of David we find a family bearing the name of Othniel, from which came Heldai the Metophathite, captain of the twelfth month (1 Ch 27:15).
IBSE, "Isaac" (in the public domain) with minor edits.