Who was the first judge of Israel after Joshua's death?

After Joshua's death, the Israelites repeatedly fell into a cycle of sin, oppression, repentance, and deliverance. God raised up judges to deliver them from their enemies. According to Judges 3:7-11, the first judge was Othniel, the son of Kenaz and younger brother (or nephew) of Caleb.

The Israelites had done evil in the sight of the Lord by serving the Baals and Asherah poles. God allowed King Cushan-Rishathaim of Mesopotamia to oppress them for eight years. When the people cried out to the Lord, He raised up Othniel as a deliverer. The Spirit of the Lord came upon Othniel; he went to war, defeated Cushan-Rishathaim, and the land had peace for forty years.

Ehud was the second judge (Judges 3:15), who delivered Israel from Moabite oppression. Deborah was the fourth judge (Judges 4-5). Gideon was the fifth judge (Judges 6-8). The biblical text explicitly places Othniel first in the sequence of judges after Joshua.