Powerful Leader

[Naez]

Generally speaking about how much stronger should a leader be than the rest of his men? For instance if I have a tribe of level 6 HD barbarians what level should the chieftain be?

[Kelb_Panthera]

Depends. How is leadership determined in that group. The leader could be lower level if wisdom is more important than strength.

[Inevitability]

Depends. A monarch might be a level 1 aristocrat while being the most powerful person in his/her kingdom. A 10th-level adventurer might have no subordinates at all. It really depends on the kind of leader.

In your example, I'd put the leader at 8-9 HD, maybe a bit higher if he leads a group where at all times someone might rise up and challenge his leadership.

[Nibbens]

Don't forget, strength might also lie in political allies, and not necessarily in a leader. Although, the common conception of a warband of barbarians would value strength or tactics over politics, but there could always be exceptions to the rule. :)

[ExLibrisMortis]

If you want the chieftain to be as strong as two CR 6 barbarians, the CR guidelines suggest CR 8 is appropriate. A CR 10 chieftain is intended to be as powerful as four CR 6 barbarians. In practice, these numbers aren't too accurate, but if you want a numerical guideline, it's there: DMG page 48.