'Second in command' in the Bible

saying, “Don’t be afraid, for my father Saul will never lay a hand on you. You yourself will be king over Israel, and I’ll be your second-in-command. Even my father Saul knows it is true.”

Joel the chief, Shapham the second in command, Janai, and Shaphat in Bashan.

Joel son of Zichri was the officer over them, and Judah son of Hassenuah was second in command over the city.