Commandant Steele

Background
Commandant Steele is the leader of the Crimson Lance forces on Pandora. It has also been speculated that she might be a Siren, a possibility hinted at by her tattoos.

Involvement
Commandant Steele is the main antagonist in Borderlands. She leads the Crimson Lance army, the lawless fighters encountered in Old Haven and beyond. She claims the Alien Technology she believes to be hidden in the Vault as the property of Atlas corporation and tries to take the vault keys by force after the last piece is collected.

The first time that she is seen is shortly after Sledge has been killed and the first Vault key piece has been acquired. At this point she transmits a message commanding that the vault key piece be turned over to the Crimson Lance, although the message is ultimately ignored and the adventure continues. It is also possible to receive a transmission en route to Sledge's Safehouse, where Steele berates the Vault hunters for accepting a mission to assassinate a "local leader".

Her later machinations involve impeding the progress of the Vault hunters, both by sending her forces to attack (in the hope of taking the vault key fragments) and by commandeering the ECHOnet. Just before the ECHOnet gets shut down it becomes clear that she is making a stronger bid for power than originally expected when Crimson Lance forces under her control are reported to be assaulting Sanctuary. Shortly thereafter she is briefly seen ordering Master McCloud to execute the Vault hunters.

When she is eventually encountered in person, the meeting is kept short; During the cut-scene, she announces that the Vault and its riches are the property of the Atlas Corporation and that the Vault hunters belong to her. After connecting the Vault key fragments together and placing them in the keyhole, pieces of the surrounding ruins merge to form a portal to the Vault. Steele is under the belief she has won and begins to celebrate when a tentacle pierces her from behind and drags her into the mouth of a huge beast known only as the Destroyer.

Quotes

 * "The contents of the Vault are rightfully the property of the Atlas Corporation. But you? You belong to me."
 * "NOW YOU WILL DIE!" - upon entering the boss area of The Backdoor.

Trivia

 * She bears the exact same tattoos as Lilith and might be the Siren she is looking for.
 * She also bears an uncanny similarity to the original design of Lilith when the game was announced to GameInformer.
 * Despite being killed by the Destroyer, if Master McCloud is fought again later, she will be there yelling "Death to all who oppose us". She also performs the same animation she does when she places the key in the vault, right before she gets stabbed.
 * Tannis once referred to her as an "Albino" due to her extremely white skin.
 * Steele does not get along with General Knoxx because she talks too much. General Knoxx states his dislike for Steele right after accepting You've Got Moxxi: Moxxi's Red Light and thanks the Vault hunters for turning her into a "meat kebab".
 * Knoxx also calls Steele a bulemic.
 * When she activates the Vault Key, her hand produces blue mist not unlike Lilith, adding to the speculation that she is a siren.
 * Originally, it was possible to see what Steele would have finished saying in the Vault if she hadn't been interrupted by the Destroyer by watching the cutscene with subtitles enabled. It seems that she was planning to throw the Vault Hunters into Tannis' jail cell to keep her company. This has since been partially fixed, though the subtitles do still show a little of what she says after she is killed (as opposed to being cut off midway).