Abimelech (Abimelek), the judge, was the son of Gideon and became a Judge of Israel, but it was not by God's will. He was Gideon's son by a concubine from Shechem.
He tried to become king, and he did reign over Israel for three years (Judges 9:22). Abimelech was one of 70 sons of Gideon's many wives. With a great desire to lead Israel, and with the help of his mother's clan in Shechem, he assassinated all his brothers but one.
Only his youngest brother, Jotham, escaped. The people of Shechem got tired of their king once he moved his residence south to Arumah, and they turned to Gaal son of Ebed, who stirred up a rebellion against Abimelech. Abimelech retaliated with a strike at Shechem, and razed the city. He then fought the rebels at Thebez.
There was a strong tower in the middle of the city, in which all the men and women of Thebez fled and shut themselves in, going up to the roof of the tower. Abimelech came right up to the door of the tower to set it on fire. But a woman dropped part of a millstone down on Abimelech's head, and it fractured his skull.
He immediately called his armor bearer and told him to kill him, so that no one would be able to say that he had been killed by a woman. His servant then killed him with a sword. These events are described in Judges 9:50-56, which is in the Old Testament of the Bible.
Next person in the Bible: Abimelech, the king