Ahithophel

Ahithophel - brother of insipidity or impiety, a man greatly renowned for his sagacity among the Jews. At the time of Absalom's revolt he deserted David (Ps. 41:9; 55:12-14) and espoused the cause of Absalom (2 Sam. 15:12). David sent his old friend Hushai[?] back to Absalom, in order that he might counteract the counsel of Ahithophel (2 Sam. 15:31-37). This end was so far gained that Ahithophel saw he had no longer any influence, and accordingly he at once left the camp of Absalom and returned to Giloh, his native place, where, after arranging his wordly affairs, he hanged himself, and was buried in the sepulchre of his fathers (2 Sam. 17:1-23). He was the type of Judas (Ps. 41:9).

From Easton's Bible Dictionary (1897)