Stella is an NCR Ranger who was captured by Caesar's Legion during the assault on Ranger station Charlie, and is now forced to fight in the Legion arena at the Fort. She is very skilled in unarmed combat and has killed many high ranking legionaries, including an elite centurion, with nothing more than her bare hands.
Stella appears only at the Fort once the Laurifer Gladiator quest is begun.
She has a number of special perks that increase her effectiveness in unarmed combat. In combat with the player, she can easily cripple limbs in one or two hits, making her a dangerous opponent.
Stella always appears in the arena, even if the player has not yet triggered the attack on Ranger station Charlie by either speaking with Ranger Andy in Novac or beginning Return to Sender.
Killing Stella does not lower the player's reputation with the NCR. However, some Legion soldiers at the Fort may be impressed and comment on her death.
Killing Stella with the machete counts for the challenge "Armed For Bear". A machete is always equipped for the arena, so you will gain a point towards this challenge without killing any important named NCR member in the wasteland.