Jacqueline Natla
Natla was one of the three legendary rulers of Atlantis, along with Tihocan and Qualopec. Together they created the Scion, a device of immeasurable power. This device was split into three parts, one for each of the rulers, representing the democracy that Atlantis lived by.
Natla abused this power, however, using the Scion to experiment in genetic engineering and create a new, improved race of Atlanteans. When they learned of this, Tihocan and Qualopec sentenced Natla to eternal imprisonment, freezing her and then burying her in present day New Mexico.
During World War II, the U.S. began testing nuclear weapons in Los Alamos, New Mexico. One of these tests happened to detonate very near to Natla's prison, freeing her from her eternal punishment.
Natla adopted the guise of Jacqueline Natla and founded Natla Technologies, a very successful company which gave her considerable financial backing. With the rest of her people long dead, there was no one to stand in the way of her experiments, and she began to research the whereabouts of the Scion.
She hired famous tomb raider Lara Croft to travel to Peru to uncover Qualopec's third, but underestimated both Lara's ability and her moral solidarity. When Larson, another of Natla's employees, revealed to Lara that there was more going on than she originally thought, Lara took up the trail of the Scion, unwilling to blindly hand over such a powerful artefact.
Lara travelled from Peru to Turkey, and then to an ancient city in Egypt collecting the three pieces of the Scion vefore Natla could. However, Natla caught up with Lara on a cliffside in Egypt and stole the completed Scion from her. Natla travelled to the great pyramid, an ancient Atlantean construction, to finally complete her experimentation.
Lara infiltrates the great pyramid and finds the control room at the top of an enormous chasm. With Natla's experiments almost complete, Lara attempts to destroy the Scion before it can be used to create Natla's hideous monsters. Natla jumps on Lara, preventing her from shooting the Scion, but apparently falling to her death far below.
However, Natla is not defeated, she reappears in a final showdown with Lara, this time revealing her true atlantean heritage. She sports red wings and blasts fire balls at Lara. When she is sufficiently damaged she plays dead, lulling Lara into a false sense of security, but will then keep fighting until she is finally killed.
Miss Jacqueline Natla will for sure make a return in tomb raider anniversary voice by Jennifer Hale.
Speculation
At the final stage of Tomb Raider Legend crates can be seen with the Natla Technologies logo referring that Amanda and Jacqueline might be related. That might be explained in Tomb Raider Anniversary. To see the logo search Amanda Entity, click on the photo and look at the crate to Lara's right and you'll see the logo.