It is not known who or of what tribe Gaal was; but it is evident that he was a man very considerable for wealth, and strength, and counsel, and interest, and ill-pleased with Abimelech's power. Went over to Shechem, by his presence and counsel to animate and assist them against Abimelech.
Related Commentaries of Judges 9:26
Judges 9:26
26 And Gaal the son of Ebed came with his brethren, and went over to Shechem: and the men of Shechem put their confidence in him.