I picked David because he was the second king of Israel, and was very important. His first action as king was to capture what is now known as the City of David in Jerusalem, fortify it and build himself a palace. The Philistines heard that David had been anointed king and attacked the kingdom, but David forced them out of Israel.
Also, Amnon, David's son, nearly killed Tamar, his sister, but Absalom, Tamar's brother, killed Amnon. Absalom fled, but Joab convinced David to bring him back. Absalom then threatened to conquer Jerusalem, and had some people supporting him. David fled the city, among with his followers.
Eventually, David had aged too much, and he had to stop fighting. He constantly felt cold, and could not warm up. At this point, one of his sons tried to proclaim himself king, but David promised his Bathsheba that her son, Solomon, would be king. He publicly made him king. He told his son his last demands, that he should follow the words of God, and to repay in kind specific people that had either wronged David or helped him. He then died, with 40 years as king.