It just came to me that the 4 most powerful demons as far as human history/records go are Lucifer, Beelzebub, Mephistopheles and Belial.
With the help of wiki:
Lucifer = Diablo
Beelzebub = Baal
Mephistopheles = Mephisto
Belial = ?
Belial is the very first fallen angel / demon (even before Lucifer) who actually encouraged Lucifer on disobeying God.
Some quotes about him (for those who hate research);
"Belial being the father of Lucifer and the angel that convinced him to wage a rebellion in Heaven against God"
"'But for corruption thou hast made Belial, an angel of hostility"
"The Satanic Bible names Belial as one of the Four Crown Princes of Hell"
Would Tyrael turn into Belial?
http://www.youtube.com/watch?v=Zfo7rtxOsT8 even in this movie, he comes right before Lucifer and is the only one named beside the devil.
I was really bored and decided to investigate, so this is all just me over thinking stuff but the research is true, wiki 'em yourself.
This post was edited by Questecura on Sep 20 2008 05:53am