Nancy Norton

 (formerly Elza Mazowalski) was a movie actress. She married Marshall Grover, thus becoming Amelia Grover's stepmother. In 1934, Professor Sternberg convinced Marshall to finance an expedition to the island of Salutua. Ostensibly, it was to explore the island and film a King Kong-like movie, with real giant animals instead of special effects. But Grover hoped the cause of the animal's growth could help restore Amelia's missing arm.

Because the Third Doctor created a time bridge to the island from UNIT in the future, several potential timelines were created. (PROSE: The Eye of the Giant)

Original timeline
She died with the expedition when the volcano on the island erupted after Brokk's ship crashed into it.

Alternate timeline 1
She made a deal with Brokk. He gave her most of his eyebrain, and sent his near mindless body to take off in his ship. The Semquess blew it up, thinking they had killed him. However, on the Constitution III after leaving Salutua, she killed Sternberg to get the Semquess drugs he had stolen. She used one to fuse with some of Brokk's eyebrain. She then mesmerised the ship's crew and went on to take over the world.

Alternate timeline 2
When the original timeline manifested forty years later, she tried to have the time bridge destroyed so her world would remain unchanged, but failed. This was because the Doctor went through the time bridge again to the Constitution III after Nancy had merged with the eyebrain. She was trying to take over the rest of the ship. The Doctor attempted to reason with her, but realized it was hopeless. He used the sonic screwdriver to shatter the eyebrain fragments, killing her.

Unfortunately, before she died, she fell on another Semquess drug ampoule. It broke and caused her to merge with the fragments and the Constitution III. The insane creation proved unstoppable, and destroyed everything on Earth.

Alternate timeline 3
Amelia Grover took the last Semquess drug and transformed into an angelic being. She stopped the Nancy-Brokk-ship hybrid and left Earth with it, hoping to eventually separate the composite creature.