Diehard

Endurance (PH) , Raised among the barbarians of Bazareene,

If reduced to -1 to -9 hit points, you may remain conscious and take a single action each round. You may roll each round to stabilize, and if you fail that roll, you lose 1 hit point. If you reach -10 or fewer hit points, you die. If you become stabilized, you are disabled until you are raised above 0 hit points.

A character without this feat is unconscious and dying at -1 to -9 hit points.

If reduced to -1 to -9 hit points, you may remain conscious and take a single action each round. You may roll each round to stabilize, and if you fail that roll, you lose 1 hit point. If you reach -10 or fewer hit points, you die. If you become stabilized, you are disabled until you are raised above 0 hit points.

A character without this feat is unconscious and dying at -1 to -9 hit points.

You can remain conscious after attacks that would fell others.