Helga Katrina Sinclair

"Commander, there were not supposed to be people down here. This changes everything."

- Helga discussing about the Atlantean natives "Nothing personal."

- Helga's last words as she fires a flare at Rourke's balloon in revenge for his treachery

Helga Katrina Sinclair is the hidden secondary antagonist of the 2001 Disney animated film, Atlantis: The Lost Empire. She was the former right-hand of Commander Lyle Tiberius Rourke.

She was voiced by Claudia Christian.

Role
Helga first appeared in the apartment of Milo James Thatch (the protagonist of the film), where she introduces herself to him and announced that her employer Preston Whitmore (who is a close friend of Milo's grandfather Thaddeus) is funding an expedition to find the lost city of Atlantis and that he wants Milo to be a part of. Sensing this as a opportunity to prove his claims about Atlantis true, Milo accepts the proposition.

During the journey, Helga is seen aiding her boss and the team into successfully locating the lost city (thanks to Milo's deciphering of the Atlantean language). However, it turns out that Helga herself is aware of the existence of a powerful crystal called the Heart of Atlantis and that she and Rourke are planning to steal it to make themselves rich. Despite her greedy nature, Helga shows some remorse when she discovered they were going to steal from an ancient yet living civilization, though this did not stop her from going along with the plan.

During the final battle, Helga uses his pistol to shoot back against the heroes, but Milo crashes his flying stone fish into the blimp, causing its to descend further. To lighten the load on the balloon, Rourke betrays Helga by attempting to throw her off, but she fights back and beats him up, berating Rourke for his treachery. However, Rourke grabs her foot and successfully throws her out, where she hits the base of the volcano.

Using the last of her strength, Helga manages to fire a flare gun at the blimp before she dies, causing the blimp to descend further. This allows Milo to defeat Rourke by crystallizing and shredding him to pieces with the blimp's propellers and return the crystal to save Atlantis from an imminent volcanic explosion.

Trivia

 * She is similar to Fidget from  The Great Mouse Detective, both being thrown overboard to "lighten the load". However, unlike Fidget, Helga didn't back down until she was thrown overboard again, and was shown to still be alive for a little after the fall.
 * Although Rourke betrayed her, some fans though that Helga reforms & joins Milo's side after she shot the balloon. This is definitely not true since she is just actually wanted to payback Rourke for throwing her overboard. It is even notable that there are some fanfictions about her survival stating she reforms & was pardoned by the Atlanteans.
 * It is even notable that some fans states that she wants to preserve Atlantis after her "reformation". This is notably shown on her article on Disney Wiki.