Who was Absalom in the Old Testament?

He was the son who rebelled against his father King David (2 Samuel ch.15) and was killed by Joab.

1 Chronicles 3:1-2New King James Version (NKJV)

The Family of David 3 Now these were the sons of David who were born to him in Hebron: The firstborn was Amnon, by Ahinoam the Jezreelitess; the second, Daniel,[a] by Abigail the Carmelitess; 2 the third, Absalom the son of Maacah, the daughter of Talmai, king of Geshur; the fourth, Adonijah the son of Haggith;