Abiathar
1 Kings 1:7 And he conferred with Joab the son of Zeruiah, and with Abiathar the priest: and they following Adonijah helped him.
the general
1 Chronicles 11:6 And David said, Whoever smites the Jebusites first shall be chief and captain. So Joab the son of Zeruiah went first up, and was chief.