Death was a Hive queen, being young, barely out of her adolescence when she made herself known, inexperienced but having the drive and decisiveness in her decisions that made her an effective enough leader that she formed her own alliance of Hives during the Wraith civil war.
With her claiming the Mantle of Coldamber, a Queen with a mind far more powerful than that of normal Queen and lineage of the First Mother Night, she was nearly unopposed in bringing the factions together until Atlantis returned to Pegasus. She is also responsible for reuniting the Wraith into a single group once again and, later on, is successful in kidnapping Dr. Rodney McKay to force him to get the Hive ship's hyperdrive working, so that the Wraith can eventually get to Earth in the hope of conquering it.
Death not only forced McKay to create a more efficient hyperdrive system for the Hive ships but also converted him into a Wraith, named Quicksilver, who served her loyally, and had him create effective shielding technology for at least a single Hive ship and Cruiser during a mission to probe Atlantis' defenses.
Both ships were destroyed in the ensuing battle between the Daedalus and the George Hammond but proved effective enough for the Wraith ships to damage the Hammond before destruction. (SGA, "The Lost")
After learning that Atlantis had gotten Hyperion's weapon, Death launched all-out attack on Atlantis. Death's fleet engaged Atlantis itself, the George Hammond, the Pride of the Genii and eventually three Wraith hive ships and three Wraith cruisers loyal to Guide. During the battle, Death's hive ship exchange fire with the Hammond, both ships causing each other great damage. Eventually Queen Waterlight's hive ship joined the attack on Death's ship and when Waterlight's ship started to fail, she and her crew boarded Death's ship to defeat her queen to queen. Teyla Emmagan followed with a boarding party from a captured cruiser while the Pride of the Genii sent a boarding party of her own that included Captain Laura Cadman and Chief Ladon Radim of the Genii. As Teyla, Waterlight and another Wraith named Bronze advanced on her control room, Death sensed their presence and personally went after the group. Death defeated Waterlight in a mental battle, but was interrupted by Teyla before she could kill the young Queen. Death was shocked to learn that Teyla was Guide's queen Steelflower and the two locked in a mental battle. Teyla learned that Death was being manipulated by the ancient Wraith Ashes and begged Death to surrender. Death refused and while her mind was powerful, she was undisciplined and inexperienced, while Teyla had greater experience and training from Guide. Teyla telepathically stopped Death's breathing, killing her when Queen Death refused to surrender. Afterwards, Teyla gave Waterlight credit for killing Death and Death's remaining forces surrendered to Waterlight and Alabaster. (SGA: "Inheritors")