The Church and God
In the last two plays leading up to Henry V (those would be Henry IV Parts 1 and 2), Henry has always had at least one mentor/father figure in his life. In Henry IV Part 1, that figure was the jolly, drunken knight, Falstaff, who taught young Henry everything he ever wanted to know about being a hoodlum. When Henry grew up, he ditched Falstaff and embraced the Lord Chief Justice as a more appropriate model of behavior in Henry IV Part 2.
Now that Henry is the King of England, though, he looks for guidance in Church leaders like the Archbishop of Canterbury. It's Canterbury, after all, who convinces Henry that he's got a legal right to claim the French throne and the Church raises the money for Henry's military campaign. We also want to point out that, throughout the play, Henry declares that the outcome of his war with France is in "God's hand" and that he's the agent of God's vengeance. So, it's safe to say that Henry sees God as the ultimate source of guidance.