Darth Bane is a human male born on the mining world Apatros. He first appeared in Dark Horse's Star Wars: Jedi vs. Sith comic series (2001), and was given a full biography in Drew Karpyshyn's Legends novel trilogy beginning with Path of Destruction (Del Rey, 2006).
The Rule of Two
Bane's contribution to the mythology is a single idea, and it is the one the prequel films run on. A Sith order of thousands, he argues, is not strong — it is a mob that consumes its own energy in infighting and cannot help but be visible. So he destroys it, and replaces it with two: a master to embody the power, an apprentice to crave it. Everything Palpatine does a thousand years later is the payoff of that decision.
The novels
Karpyshyn's trilogy — Path of Destruction, Rule of Two, Dynasty of Evil — is the rare Star Wars series with no heroes in it at all. It follows Bane from an indentured miner through the Sith academy on Korriban to the Battle of Ruusan, and then follows his apprentice Zannah for decades as she waits for the moment the Rule of Two requires of her. It is cold, disciplined and unusually well plotted.
Canon status
Bane straddles the line. The doctrine itself is firmly canon — Yoda states it in The Phantom Menace as "always two there are, no more, no less: a master and an apprentice", though the phrase "Rule of Two" is never spoken in the film — and Bane appeared as a spectral vision in Star Wars: The Clone Wars, which is canon. His detailed biography, the novels, Apatros, Zannah and the rest are Star Wars Legends.
Reading note
Start with Path of Destruction. It requires no other reading and is the best standalone entry point on the entire Legends shelf.
