I dunno much about Darth Bane - other than that he revolutionized the Sith Order with the master and apprentice rule - as well as the title of Darth. Until KOTOR came along, lol.
Dark Empire Sidious is kind of like Nihilius. I don't see how anyone can really defeat or kill him - simply because Nihilius drains their Force powers and Sidious can hurl people across time and space.
But. Nihilius met his demise - as did Sidious. Sidious was shot in the back by Han Solo while Sidious was taking on (and defeating) Luke's Jedi Order. He nearly killed Luke himself and moved in for Anakin Solo. But Han, enraged, shot him in the back. Sidious then lunged for the baby, dying, ready to transfer his consciousness into him.
But some Jedi (I can't remember his long first time) named Brand intercepted Sidious and held him back long enough for Sidious to die a supposedly final death. But Brand died in the process.