Mammon

Paradise Lost describes Mammon as:
"Mammon, the least erected Spirit that fell
From heav'n, for ev'n in heav'n his looks and thoughts [ 680 ]
Were always downward bent, admiring more
The riches of Heav'ns pavement, trod'n Gold,
Then aught divine or holy else enjoy'd
In vision beatific: by him first
Men also, and by his suggestion taught, [ 685 ]
Ransack'd the Center, and with impious hands
Rifl'd the bowels of thir mother Earth
For Treasures better hid."

in heaven he did not worship and follow god, he focused on the beauty of it and basically everything but the divine.
because of him people dig up the earth and search everything they can in order to find riches.
it also says that he was leading the rest so he must have some power in hell.