Quick final boss

[Zanthy1]

So i'm running a short players challenge campaign, simply the story is fine, I just need a super cool final boss. I am expecting them to be around lvl 5 when they reach him (or her). Using only the core phb1, monster manual 1, and dmg 1.

What sort of suggestions?

Thanks!

[D@rK-SePHiRoTH-]

Need more info. Why is this enemy a final boss? What did he previously do? Is it humanoid? What is his/her purpose?

[sol_kanar]

A White Dragon, well-played, with good feats, might be a cool boss (no pun intended). Note that it might not fit into the flavor/story of your adventure.