Lalah's design is simple yet unique. This page covers the history of that design.

Tomino’s original Lalah concept was a thirteen-year-old girl named "Asteroid Lalah" with blue or blonde hair. Asteroid Lalah was an esper who died after Amuro developed romantic feelings for her, but her role in the story was different in the earliest drafts. As the story developed, Lalah would later get involved with the Red Comet, and she would become older as well, and her appearance and ethnic background changed. It was scriptwriter Yu Yamamoto who decided Lalah should be Indian.

Yamamoto: When we were deciding on Lalah, I was adamant that she must be of Indian descent from the very beginning, but Tomino-san was adamant about blonde hair being better and he wasn't keen on it. I thought, "Oh, this isn't going to work," but then Yasuhiko-san's drawing of Lalah turned out to be Indian after all, so I was really happy (laughs).

I’m not sure if that drawing of Yasuhiko’s was made before or after this Lalah concept art by Tomino:

In this concept art, you can see Lalah has her bindi-like birthmark. For more information on the spiritual inspirations behind her character, see the Lalah and Eastern Spirituality page.

Either way, Lalah's final design is likely inspired by Mari Paindavoine from The Story of Perrine, an anime that Tomino did some storyboarding for.

Although they look similar, they couldn’t be more different in personality. Mari is a very anxious woman who cries frequently and parentifies her child. Lalah is more strong and stoic.

So, in the end, Lalah's cute and classic final design was a collaboration between scriptwriter Yamamoto, director Tomino and character designer Yasuhiko. Lalah is considered a "Tomino character" but she was also created by Yamamoto and the other writers.

Lalah wears a military uniform in Encounters in Space.

Lalah looks basically the same in the movie Char's Counterattack, but she is no longer wearing shoes.

Lalah also looks similar in the anime Gundam the Origin, but her dress has short sleeves.

Lalah appears in the form of a coscoroba swan in the movie Char's Counterattack. Coscorobas are easy to identify because they look more like ducks than other swan species.

In the manga Gundam the Origin, she has more of a traditional swan shape, probably a whooper swan like the one she watched in First Gundam.

In one of the ending themes for the TV series Gundam the Origin, she transforms into a white bird of some kind and flies away. Maybe a swan, maybe a seagull, maybe something else?